---
title: "UoMD — Units of Measurement Directive"
description: "The Units of Measurement Directive sets the SI-based legal units for every measurement or indication of quantity in the EU, binding manufacturers, importers, distributors, service providers and public bodies. It has applied since 1 October 1981; supplementary non-metric indications remain authorised without end date, and the 2018 SI base unit definitions have applied since 13 June 2020."
type: "guide"
url: "https://www.conphora.com/regulations/uomd/"
markdown: "https://www.conphora.com/regulations/uomd.md"
locale: "en"
language: "en"
published: "1979-12-21"
updated: "2026-09-13"
author: "Conphora compliance team"
publisher: "Conphora"
reference: "Directive 80/181/EEC"
celex: "31980L0181"
source: "https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:31980L0181"
tags: ["UoMD", "Labelling & Packaging"]
license: "Free to quote with attribution and a link to the page"
---

# UoMD — Units of Measurement Directive

The Units of Measurement Directive sets the SI-based legal units for every measurement or indication of quantity in the EU, binding manufacturers, importers, distributors, service providers and public bodies. It has applied since 1 October 1981; supplementary non-metric indications remain authorised without end date, and the 2018 SI base unit definitions have applied since 13 June 2020.

## Key facts

- **Official title:** Council Directive of 20 December 1979 on the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC (80/181/EEC)
- **Reference:** Directive 80/181/EEC
- **CELEX:** 31980L0181
- **Act type:** Directive
- **In force:** 1979-12-21
- **Applies from:** 1981-10-01
- **Enforced by:** The directive contains no enforcement or penalty article of its own: Member States adopt and apply the transposing laws under Article 7 and enforce them through their own metrology and market surveillance authorities. Since 16 July 2021 those authorities act with the powers of Regulation (EU) 2019/1020, which lists Directive 80/181/EEC as point 6 of its Annex I; the directive is not in the Article 4(5) list, so the regulation's duty to have an economic operator established in the Union does not attach to it, and it is not in Annex II, so the penalty obligation of Article 41 of that regulation does not extend to it either. In Denmark the directive is implemented by executive order nr. 866 of 11 May 2021 on the international system of units, SI, and other legal units, issued by Sikkerhedsstyrelsen under section 18(1) and section 23(3) of act nr. 1518 of 18 December 2018 on business promotion, whose section 18(1) then required the minister to make rules on metrology, including which units of measurement apply. That power has since moved: act nr. 782 of 4 May 2021 transferred metrology to the product act with effect from 1 July 2021, where the minister's rule-making power for units of measurement is now section 8a and units of measurement are product area nr. 19 of section 2(1). Section 7(1) of act nr. 782/2021 keeps rules made under chapter 8 of the business promotion act in force until they are repealed or replaced by rules made under the product act, which is why order nr. 866/2021 — issued seven weeks before the transfer took effect — still stands, and why section 18 of the current consolidation of the business promotion act (LBK nr. 230 of 29 February 2024) no longer contains a metrology power at all. So the two instruments are not two parallel regimes but a transition: the order is the substantive rule, the product act supplies the control authority, the powers and the penalties. The product act (lov om produkter og markedsovervågning) names Erhvervsstyrelsen as the control authority, and the tasks are carried out by Sikkerhedsstyrelsen, since January 2026 the department Markedsovervågning of Erhvervsstyrelsen, which may also delegate metrology control to another public authority or to a public or private undertaking. The toolkit is orders to warn users, stop misleading marketing, remedy what does not meet the rules, stop sales, withdraw, recall or destroy the product, prohibitions on placing on the market, making available, supplying or putting into use, and orders to the owner of an instrument used for payment-based measurement. The SI order itself provides only for fines. The product act's imprisonment of up to 2 years in aggravating circumstances attaches to the offences listed in its section 37(1)(1) and (3) to (10) — in practice, for this product area, a breach of the act's own product requirements, a failure to give the control authority information or access, or a failure to comply with its decisions — and units of measurement are inside the product-area band of section 37(2). It does not attach to a breach of the SI order's own rules, and the points that rest on Article 4 and Article 5 of Regulation (EU) 2019/1020 cannot apply here, because the directive is not in the Article 4(5) list.
- **Category:** Labelling & Packaging

## Who it applies to

**Covered by the act:** Measuring instruments used, measurements made and indications of quantity expressed in units of measurement, wherever they occur; since Directive 2009/3/EC replaced Article 2(a) the directive is no longer tied to particular fields of Union action; Indications of quantity on a product, its packaging and its label, in its instructions and technical documentation, and in the offers, listings and marketing that carry a size, weight, volume, length, area, capacity or similar figure; The units themselves: Chapter I of the Annex, built on the seven SI base units, their decimal multiples and submultiples with the twenty prefixes from yotta to yocto, the SI derived units with special names, the litre, tonne and bar, the units defined on the basis of SI units such as the degree, minute, hour and day, the electronvolt and the unified atomic mass unit, the units permitted in specialised fields only and the compound units formed from all of them; Every party that expresses such an indication: manufacturers and packers, importers, distributors and retailers, service providers, laboratories and public administration

**Derived and downstream products:** The directive settles which unit may be used, not whether a quantity has to be declared at all or where on the pack it must appear; the sector rules that require a net quantity declaration decide that, and this directive decides only the unit it is expressed in (Art. 1 and Art. 2(a)); A supplementary indication is one or more indications of quantity in units not contained in Chapter I accompanying an indication in a Chapter I unit; it is authorised without any end date, but the Chapter I indication must predominate and the characters of the other indication must be no larger than those used for the Chapter I figure (Art. 3(1), 3(2) and 3(4)); Member States may require measuring instruments to bear indications of quantity in a single legal unit; Denmark has not used that option, its SI order repeating only the predominance rule (Art. 3(3); executive order nr. 866/2021, § 3); The Chapter II units are legal only in the Member States where they were authorised on 21 April 1973, which recital 1 of Directive 2009/3/EC identifies as the United Kingdom and Ireland. Article 1(b) attaches the exemption to Member States, so within the Union today it is Ireland that the chapter can still reach; the United Kingdom left the Union on 31 January 2020, and whatever status the pint, the mile and the troy ounce have there now is a matter of United Kingdom law and not of this directive. The Danish order reproduces only Chapter I, so none of them is a legal unit in Denmark (Art. 1(b); Directive 2009/3/EC, recitals 1 and 10; executive order nr. 866/2021, Annex 1); The Chapter III and Chapter IV units were legal only until a date each Member State fixed, which could not be later than 31 December 1994 and 31 December 1999; those windows have closed (Art. 1(c) and (d)); The directive does not affect the use in air and sea transport and rail traffic of units other than those it makes compulsory where they are laid down in international conventions or agreements binding the Union or the Member States (Art. 2(b); executive order nr. 866/2021, § 2); Units that are not or are no longer legal may still be used for products and equipment already on the market or in service on the date the directive was adopted and for components and parts needed to supplement or replace parts of them, although legal units may be required for the indicators of measuring instruments; the Danish order fixes that cut-off at 1 July 1977 (Art. 4; executive order nr. 866/2021, § 4)

**Roles under the act:**

- **Manufacturer or packer that sets the quantity indications** — The directive defines no economic operators. Article 1 obliges legal units to be used for expressing quantities and Article 2(a) attaches that obligation to measuring instruments used, measurements made and indications of quantity expressed in units of measurement, so the duty falls first on the party that decides the figures on the product, its packaging, its instructions and its technical documentation.
- **Importer bringing goods into the Union** — Whoever brings a product into the Union market carries the same Article 1 obligation for the indications of quantity on what it supplies here; goods prepared for a third-country market often carry a non-metric figure as the governing indication, and Article 4 allows a non-legal unit only for products and equipment already on the market or in service when the directive was adopted and for components and parts that supplement or replace parts of them.
- **Distributor, retailer or online seller** — Whoever makes the goods available further down the chain and repeats or restates a quantity, on a shelf-edge label, in a listing, in marketing or on a relabelled or repacked unit, expresses an indication of quantity within the meaning of Article 2(a) and must use a Chapter I unit as the predominant figure.
- **Public administration, health and safety bodies, laboratories and service providers** — Since Directive 2009/3/EC replaced Article 2(a) the obligations are no longer limited to any specific field of Union action: they relate to measuring instruments used, measurements made and indications of quantity expressed in units of measurement, whoever uses, makes or expresses them, which covers administrative, public-health, safety and laboratory use.

## Key dates

- 1979-12-20: Council Directive 80/181/EEC adopted, replacing Directive 71/354/EEC and published in OJ L 39 of 15 February 1980
- 1979-12-21: Entry into force and date of effect of the directive as recorded on EUR-Lex
- 1981-06-30: Deadline for Member States to adopt and publish the laws, regulations and administrative provisions needed to comply, which had to be in place before 1 July 1981, and to inform the Commission
- 1981-10-01: Member States apply their transposing provisions and Directive 71/354/EEC is repealed
- 1984-12-20: Council Directive 85/1/EEC in force: it does three things — it replaces the definition of the metre in Chapter I point 1.1 with the 1983 definition (the length of the path travelled in a vacuum by light during 1/299 792 458 seconds), it adds the millimetre of mercury for blood pressure and the pressure of other body fluids (1 mm Hg = 133,322 Pa) and the barn for effective cross-sectional area (1 b = 10⁻²⁸ m²) to the specialised units of Chapter I point 4 and rewrites the note on prefixes so that they may be used with those units except the millimetre of mercury, with the multiple of 10² ares called a hectare, and it deletes the blood-pressure unit from Chapter II and replaces that chapter's note; Member States had to bring the measures into force on 1 July 1985
- 1989-11-30: Council Directive 89/617/EEC notified and in force: it replaces Article 1(b) and (c) with three points (b), (c) and (d), so the Chapter II units stay legal until a date the Member States concerned fix and the Chapter III units and the new Chapter IV units until dates no later than 31 December 1994 and 31 December 1999, extends the authorisation of supplementary indications in Article 3(2) from 31 December 1989 to 31 December 1999 and deletes Article 3(5), updates the ISO 2955 reference in Article 5 from 1 March 1974 to 15 May 1983, deletes the second subparagraph of Article 6, and in the Annex replaces Chapter II, deletes the fathom from Chapter III and adds Chapter IV; Member States had 24 months from notification
- 1994-12-31: Last date a Member State could fix for the Chapter III units, the imperial length, area, volume, mass and energy units of Article 1(c); after the date fixed by each State they stopped being legal units
- 1999-12-31: Last date a Member State could fix for the Chapter IV units of Article 1(d), the fathom for marine navigation, the pint and fluid ounce for certain drinks in returnable containers, the gill for spirit drinks, the ounce and pound for goods sold loose in bulk and the therm for gas supply
- 2000-02-09: Directive 1999/103/EC, adopted on 24 January 2000 despite its 1999 number, in force on the day of publication: it extends the authorisation of supplementary indications in Article 3(2) from 31 December 1999 to 31 December 2009, inserts Article 6a on the further examination of implementation and in particular of supplementary indications under the committee procedure of Article 18 of Directive 71/316/EEC (since Directive 2009/34/EC, its Article 17(1) and the committee of its Article 16), and amends the Annex in Chapter I point 1.1.1 (the Celsius temperature definition), point 1.2.1 (radian and steradian), the prefix table of point 1.3 and point 3 on the electronvolt and the unified atomic mass unit; to be transposed before 9 February 2001
- 2009-05-27: Directive 2009/3/EC in force: it removes the end date for the Chapter II units and for supplementary indications, rewrites Article 2(a) so the directive is not limited to specific fields of Union action, inserts the Article 6b reporting duty, deletes the acre from Chapter II and rewrites the SI derived units of Chapter I
- 2010-01-01: Member States apply their measures transposing Directive 2009/3/EC, after a transposition deadline of 31 December 2009
- 2019-05-20: The new definitions of the SI base units adopted at the 26th meeting of the General Conference on Weights and Measures in 2018 become effective at international level, based on fixed numerical values of seven defining constants
- 2019-08-13: Commission Directive (EU) 2019/1258 in force: it replaces Chapter I section 1.1 of the Annex with the constant-based definitions of the seven SI base units and the degree Celsius
- 2019-12-31: Deadline for the Commission report to the European Parliament and the Council on market developments relating to the directive and its implementation, with proposals where appropriate
- 2020-05-13: Deadline for Member States to adopt and publish the provisions transposing Commission Directive (EU) 2019/1258
- 2020-06-13: Member States apply the provisions transposing Commission Directive (EU) 2019/1258; this is the date of the consolidated version of the directive in force today
- 2021-05-14: Danish executive order nr. 866 of 11 May 2021 on the international system of units, SI, and other legal units in force, replacing order nr. 618 of 13 May 2020; it repeats the obligation to use the prescribed units, the transport exception, the supplementary indication rules and a fine for breaches
- 2021-07-16: Regulation (EU) 2019/1020 applies: Directive 80/181/EEC is point 6 of its Annex I, so national market surveillance authorities exercise the regulation's investigation and enforcement powers for it; the directive is in neither the Article 4(5) list nor Annex II
- 2026-01-01: Sikkerhedsstyrelsen becomes the department Markedsovervågning of Erhvervsstyrelsen and continues the same tasks, including legal metrology

## What you must do

### Manufacturer or packer that sets the quantity indications

- Express every quantity on the product, its packaging, its label, its instructions and its technical documentation in a legal unit of measurement, that is a unit of Chapter I of the Annex, unless one of the restricted chapters or the transport exception applies to that specific case.
- Build the figures on the seven SI base units, the second, metre, kilogram, ampere, kelvin, mole and candela, and on the units derived from them: the SI derived units with special names from the radian to the katal, the degree Celsius, the decimal multiples formed with the twenty prefixes from yotta to yocto, and the specially authorised names litre, tonne and bar.
- Use the units permitted in specialised fields only inside those fields: the dioptre for the vergency of optical systems, the metric carat for the mass of precious stones, the are for the area of farmland and building land, the tex for the mass per unit length of textile yarns and threads, the millimetre of mercury for blood pressure and the pressure of other body fluids, and the barn for effective cross-sectional area.
- Where a non-metric figure is kept for an export market or a familiar audience, present it as a supplementary indication next to the Chapter I figure, let the Chapter I indication predominate and print the other indication in characters no larger than those of the corresponding Chapter I indication.
- Follow the composition rules of the Annex: form the multiples and submultiples of the unit of mass by attaching prefixes to the word gram and their symbols to the symbol g, attach a prefix to the numerator, the denominator or both parts of a unit written as a fraction, and never use compound prefixes formed by juxtaposing several prefixes.
- Where the indication appears on the display or indicator of a measuring instrument, check whether the Member State has required indications of quantity in a single legal unit; in Denmark the SI order makes clear which SI unit is meant and offers the writing rules of its Annex 2, and legal units may be required for the indicators of measuring instruments even for old equipment covered by the Article 4 exception.
- Treat the unit question as separate from the declaration question: the sector rules decide whether a net quantity or a dimension has to be declared and in what form, this directive decides only the unit the figure is expressed in, so read the two together rather than in isolation.

### Importer bringing goods into the Union

- Before placing goods on the Union market, check every quantity indication that travels with them, on the product, the packaging, the label, the manual and the accompanying documents, and correct any figure that is not expressed in a legal unit.
- For goods prepared for a third-country market, do not simply keep the non-metric figure: either replace it with a Chapter I figure or add the Chapter I figure and make it the predominant one, with the non-metric characters no larger.
- Do not rely on the Article 4 grandfathering unless it actually fits: it covers products and equipment already on the market or in service when the directive was adopted, and components and parts needed to supplement or replace parts of those products, and in Denmark is written as goods and equipment already placed on the market or taken into use before 1 July 1977.
- Do not treat the Chapter II units as generally available: the mile, yard, foot, inch, pint and troy ounce are legal units only in the Member States that authorised them on 21 April 1973, and the Danish order reproduces Chapter I only.
- Cooperate with the market surveillance authority: since 16 July 2021 the directive is point 6 of Annex I to Regulation (EU) 2019/1020, so the authority can require information and documents, carry out checks, require corrective action, prevent the product from being made available and have it withdrawn, recalled or destroyed.

### Distributor, retailer or online seller

- Make sure that shelf-edge labels, catalogues, online listings and marketing copy aimed at end users in the Union give sizes, weights, volumes, capacities and other quantities in legal units; the obligation follows the indication of quantity, not the surface it appears on.
- When you relabel, repack or split a product, carry the legal unit across to the new label and keep any non-metric figure subordinate to it, in characters no larger than the corresponding Chapter I indication.
- Do not restate a supplier's quantity in a unit of your own choosing, and do not convert a metric figure into a non-metric one as the only indication; a non-metric figure standing alone is not a supplementary indication.
- Where a Danish customer is buying on the basis of a measurement, remember that the control authority can order the owner of the measuring instrument to bring it into conformity and can forbid its use where payment is based on the measurement.
- Keep an eye on whether the goods are destined for a Member State where the Chapter II units are still legal; outside those States the mile, pint and troy ounce may appear only as supplementary indications.

### Public administration, health and safety bodies, laboratories and service providers

- Public administration, health and safety bodies, laboratories and service providers use legal units for the instruments they use, the measurements they make and the quantities they state; since Directive 2009/3/EC rewrote Article 2(a) the obligation is not limited to any specific field of Union action.
- Medical and clinical use follows the same Annex: the millimetre of mercury remains legal for blood pressure and the pressure of other body fluids, and it is the one specialised unit that may not be combined with a prefix.
- Laboratories may use the units whose values in SI are obtained experimentally, the electronvolt for energy and the unified atomic mass unit for mass, with the prefixes of point 1.3, and the katal for catalytic activity, which the General Conference on Weights and Measures adopted in 1999 to give medicine and biochemistry one harmonised unit.
- In air and sea transport and rail traffic, units other than the compulsory ones may be used where they are laid down in international conventions or agreements binding the Union or the Member States; the exception is limited to those units and does not open the door to non-metric labelling generally.
- Where an authorised representative or another party answers for a product in the Union, note that Directive 80/181/EEC is not in the Article 4(5) list of Regulation (EU) 2019/1020, so that regulation's duty to have an economic operator established in the Union does not follow from this directive; it may still follow from another act that applies to the same product.

## Requirements

Each duty above as an identified requirement (17); ids are permanent and shared with the compliance engine.

### data

- `uomd-mfr-express-quantity-product` (Manufacturer or packer that sets the quantity indications, product, before-market) — Express every quantity on the product, its packaging, its label, its instructions and its technical documentation in a legal unit of measurement, that is a unit of Chapter I of the Annex, unless one of the restricted chapters or the transport exception applies to that specific case. [Art. 1 and Art. 2(a)]
- `uomd-mfr-build-figures-seven` (Manufacturer or packer that sets the quantity indications, product, before-market) — Build the figures on the seven SI base units, the second, metre, kilogram, ampere, kelvin, mole and candela, and on the units derived from them: the SI derived units with special names from the radian to the katal, the degree Celsius, the decimal multiples formed with the twenty prefixes from yotta to yocto, and the specially authorised names litre, tonne and bar. [Annex, Chapter I, points 1.1 to 1.4]
- `uomd-mfr-use-units-permitted` (Manufacturer or packer that sets the quantity indications, product, before-market) — Use the units permitted in specialised fields only inside those fields: the dioptre for the vergency of optical systems, the metric carat for the mass of precious stones, the are for the area of farmland and building land, the tex for the mass per unit length of textile yarns and threads, the millimetre of mercury for blood pressure and the pressure of other body fluids, and the barn for effective cross-sectional area. [Annex, Chapter I, point 4]
- `uomd-mfr-present-supplementary-indication` (Manufacturer or packer that sets the quantity indications, product, before-market) — Where a non-metric figure is kept for an export market or a familiar audience, present it as a supplementary indication next to the Chapter I figure, let the Chapter I indication predominate and print the other indication in characters no larger than those of the corresponding Chapter I indication. [Art. 3(1), 3(2) and 3(4)]
- `uomd-mfr-follow-composition-rules` (Manufacturer or packer that sets the quantity indications, product, before-market) — Follow the composition rules of the Annex: form the multiples and submultiples of the unit of mass by attaching prefixes to the word gram and their symbols to the symbol g, attach a prefix to the numerator, the denominator or both parts of a unit written as a fraction, and never use compound prefixes formed by juxtaposing several prefixes. [Annex, Chapter I, point 1.3]
- `uomd-mfr-check-whether-member` (Manufacturer or packer that sets the quantity indications, product-market, before-market) — Where the indication appears on the display or indicator of a measuring instrument, check whether the Member State has required indications of quantity in a single legal unit; in Denmark the SI order makes clear which SI unit is meant and offers the writing rules of its Annex 2, and legal units may be required for the indicators of measuring instruments even for old equipment covered by the Article 4 exception. [Art. 3(3) and Art. 4; https://www.retsinformation.dk/eli/lta/2021/866 · § 3, stk. 4, and bilag 2]
- `uomd-imp-simply-keep-non-metric` (Importer bringing goods into the Union, product, before-market) — For goods prepared for a third-country market, do not simply keep the non-metric figure: either replace it with a Chapter I figure or add the Chapter I figure and make it the predominant one, with the non-metric characters no larger. [Art. 3(1) and 3(4)]
- `uomd-imp-treat-chapter-units` (Importer bringing goods into the Union, product-market, before-market) — Do not treat the Chapter II units as generally available: the mile, yard, foot, inch, pint and troy ounce are legal units only in the Member States that authorised them on 21 April 1973, and the Danish order reproduces Chapter I only. [Art. 1(b) and Annex, Chapter II; https://www.retsinformation.dk/eli/lta/2021/866 · bilag 1]
- `uomd-dist-make-sure-shelf-edge` (Distributor, retailer or online seller, product, at-listing) — Make sure that shelf-edge labels, catalogues, online listings and marketing copy aimed at end users in the Union give sizes, weights, volumes, capacities and other quantities in legal units; the obligation follows the indication of quantity, not the surface it appears on. [Art. 1 and Art. 2(a); https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0003 · recital 2 and Art. 1(2)]
- `uomd-dist-repack-split-product` (Distributor, retailer or online seller, product, before-market) — When you relabel, repack or split a product, carry the legal unit across to the new label and keep any non-metric figure subordinate to it, in characters no larger than the corresponding Chapter I indication. [Art. 3(1) and 3(4)]
- `uomd-dist-restate-suppliers-quantity` (Distributor, retailer or online seller, product, at-listing) — Do not restate a supplier's quantity in a unit of your own choosing, and do not convert a metric figure into a non-metric one as the only indication; a non-metric figure standing alone is not a supplementary indication. [Art. 3(1) and 3(2)]

### verification

- `uomd-imp-check-quantity-indication` (Importer bringing goods into the Union, product, before-market) — Before placing goods on the Union market, check every quantity indication that travels with them, on the product, the packaging, the label, the manual and the accompanying documents, and correct any figure that is not expressed in a legal unit. [Art. 1 and Art. 2(a)]
- `uomd-dist-keep-eye-whether` (Distributor, retailer or online seller, product-market, before-market) — Keep an eye on whether the goods are destined for a Member State where the Chapter II units are still legal; outside those States the mile, pint and troy ounce may appear only as supplementary indications. [Art. 1(b) and Art. 3; https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0003 · recital 1]

### standing

- `uomd-imp-cooperate-market-surveillance` (Importer bringing goods into the Union, company, ongoing) — Cooperate with the market surveillance authority: since 16 July 2021 the directive is point 6 of Annex I to Regulation (EU) 2019/1020, so the authority can require information and documents, carry out checks, require corrective action, prevent the product from being made available and have it withdrawn, recalled or destroyed. [Art. 2(1), Art. 14, Art. 16 and Annex I point 6]

## Penalties

The directive itself lays down no penalties and no enforcement procedure. Article 7 requires Member States to adopt, publish and apply the laws, regulations and administrative provisions needed to comply with it, and to inform the Commission of them and of any draft measures in the field, so the sanction sits in national law. Since 16 July 2021 the surveillance side rests on Regulation (EU) 2019/1020: the directive is point 6 of its Annex I, which makes it Union harmonisation legislation for the purposes of the regulation, so market surveillance authorities hold the Article 14 powers to require documents and information, carry out checks and enter premises, and the Article 16 measures to require corrective action, to prevent the product being made available, to withdraw, recall or destroy it, to set prior conditions for making it available and to warn end users. The directive is not listed in Annex II to that regulation, so the Article 41 duty to lay down penalties for infringements does not reach it through the regulation, and it is not in the Article 4(5) list either. In Denmark, executive order nr. 866 of 11 May 2021 punishes with a fine a breach of the duty to use the prescribed units and of the predominance rule, and fines anyone who intentionally or through gross negligence states an SI unit in a way designed to mislead, with criminal liability for companies under chapter 5 of the criminal code; the order is issued under section 18(1) and section 23(3) of act nr. 1518 of 18 December 2018 on business promotion, whose section 18(1) then required the minister to make rules on metrology, including which units of measurement apply. That power has since moved: act nr. 782 of 4 May 2021 transferred metrology to the product act with effect from 1 July 2021, where the minister's rule-making power for units of measurement is now section 8a and units of measurement are product area nr. 19 of section 2(1). Section 7(1) of act nr. 782/2021 keeps rules made under chapter 8 of the business promotion act in force until they are repealed or replaced by rules made under the product act, which is why order nr. 866/2021 — issued seven weeks before the transfer took effect — still stands, and why section 18 of the current consolidation of the business promotion act (LBK nr. 230 of 29 February 2024) no longer contains a metrology power at all. So the two instruments are not two parallel regimes but a transition: the order is the substantive rule, the product act supplies the control authority, the powers and the penalties. The product act names Erhvervsstyrelsen as the control authority and lets it warn users, stop misleading marketing, order the fault remedied, stop sales, order withdrawal, recall or destruction, prohibit placing on the market, making available, supply or putting into use, and order the owner of an instrument used for payment-based measurement to bring it into conformity or forbid its use; breaches of those decisions are fined and, in aggravating circumstances, punished with imprisonment of up to 2 years. Since January 2026 Sikkerhedsstyrelsen is the department Markedsovervågning of Erhvervsstyrelsen.

## Checklist

1. List every place a measured quantity appears for a given product: net contents, dimensions, capacity, dosage, area, mass per length, pressure, energy, on the pack, on the label, in the manual, in the spec sheet, on the shelf edge and in the online listing.
2. Make the governing figure a Chapter I unit in each of those places, built on the seven SI base units and the units derived from them, and use the specialised units such as the dioptre, metric carat, are, tex, millimetre of mercury and barn only within their own field (Annex, Chapter I, points 1 and 4).
3. Where a non-metric figure is kept, print it as a supplementary indication beside the metric one, keep the metric indication predominant and keep the non-metric characters no larger than the corresponding metric ones (Article 3(1) and 3(4)).
4. Check the composition rules: mass multiples are formed on the word gram and the symbol g, a prefix may sit in the numerator or the denominator of a fraction unit or in both, and compound prefixes are not allowed (Annex, Chapter I, point 1.3).
5. Treat the mile, yard, foot, inch, pint and troy ounce as legal units only in the Member States that authorised them on 21 April 1973, and the acre, gallon, quart, gill, fluid ounce, pound, fathom and therm as no longer legal anywhere, since the Article 1(c) and 1(d) windows closed at the end of 1994 and 1999.
6. Confirm whether the Member State you sell into has required measuring instruments to carry a single legal unit under Article 3(3); Denmark has not, and its SI order instead asks that the SI unit be stated clearly and offers writing rules for symbols and compound units.
7. Keep the air, sea and rail exception to what it says: units other than the compulsory ones are allowed there only where an international convention or agreement binding the Union or the Member States lays them down (Article 2(b)).
8. Do not stretch the Article 4 grandfathering: it covers products and equipment already on the market or in service when the directive was adopted and the parts that supplement or replace parts of them, with 1 July 1977 as the Danish cut-off, and legal units may still be required for the indicators of measuring instruments.
9. Check that the technical documentation, drawings and calculations that support a declaration of conformity under another act use the same legal units as the pack, since the obligation also covers measurements made and instruments used.
10. Read this directive together with the sector rules that decide whether and how a quantity must be declared; those rules set the declaration, this one sets the unit.

## Questions

### Which units of measurement are legal in the EU?

The units of Chapter I of the Annex. They start from the seven SI base units, the second, metre, kilogram, ampere, kelvin, mole and candela, add the degree Celsius and the SI derived units with special names, twenty-one of them from the radian and steradian through the newton, pascal, joule, watt, volt, ohm, farad, weber, tesla, henry, lumen, lux, becquerel, gray and sievert to the katal, and allow the decimal multiples and submultiples formed with the twenty prefixes from yotta to yocto. Chapter I also carries the specially authorised litre, tonne and bar, the units defined on the basis of SI units that are not decimal multiples of them, the revolution, grade or gon, degree, minute and second of angle, minute, hour and day, the electronvolt and the unified atomic mass unit whose values are obtained experimentally, the six units permitted in specialised fields only, the dioptre, metric carat, are, tex, millimetre of mercury and barn, and every compound unit formed by combining them.

### Can I still show inches, pounds or fluid ounces next to the metric figure?

Yes. A supplementary indication, meaning one or more indications of quantity in units not contained in Chapter I accompanying an indication in a Chapter I unit, is authorised, and Directive 2009/3/EC removed the end date of 31 December 2009 that used to hang over it, so the authorisation now runs without a time limit. The reason given is to avoid obstacles for Union undertakings exporting to third countries that require other units, and to let new metric units developed internationally be introduced gradually. Two conditions apply: the Chapter I indication must predominate, and the indications in units not listed in Chapter I must be in characters no larger than those of the corresponding Chapter I indication. A non-metric figure printed on its own is not a supplementary indication.

### Did the pint, the mile and the troy ounce have to disappear?

No. Article 1(b) makes the Chapter II units legal in those Member States where they were authorised on 21 April 1973: the mile, yard, foot and inch for road traffic signs and distance and speed measurement, the pint for the dispense of draught beer and cider and for milk in returnable containers, and the troy ounce for transactions in precious metals. Directive 2009/3/EC removed the requirement on those States to fix an end date, noting that the exemptions concerned the United Kingdom and Ireland and that their local character and the limited number of products meant they were no barrier to trade; the same directive deleted the acre from Chapter II, because it was no longer used for land registration there. Article 1(b) attaches the exemption to Member States, so within the Union today it is Ireland that the chapter can still reach; the United Kingdom left the Union on 31 January 2020, and whatever status the pint, the mile and the troy ounce have there now is a matter of United Kingdom law and not of this directive. The units of Chapters III and IV were different: they could only run until a date each Member State fixed, no later than 31 December 1994 and 31 December 1999.

### What changed with the 2019 redefinition of the SI base units?

Commission Directive (EU) 2019/1258 replaced section 1.1 of Chapter I with the definitions the General Conference on Weights and Measures adopted at its 26th meeting in 2018, effective internationally from 20 May 2019. The seven base units are now fixed by the numerical values of seven defining constants: the caesium frequency of 9 192 631 770 hertz for the second, the speed of light in vacuum of 299 792 458 metres per second for the metre, the Planck constant of 6,626 070 15 times 10 to the power minus 34 joule second for the kilogram, the elementary charge of 1,602 176 634 times 10 to the power minus 19 coulomb for the ampere, the Boltzmann constant of 1,380 649 times 10 to the power minus 23 joule per kelvin for the kelvin, the Avogadro number of 6,022 140 76 times 10 to the power 23 entities for the mole, and a luminous efficacy of 683 lumen per watt at 540 terahertz for the candela. Member States had to transpose it by 13 May 2020 and apply it from 13 June 2020, deliberately on the same date everywhere. The names, symbols and values of the units did not change, only the way they are defined.

### Does the directive apply to advertising and online listings, or only to labels?

It is not written by surface. Article 1 says legal units must be used for expressing quantities, and Article 2(a), as replaced by Directive 2009/3/EC, ties the obligation to measuring instruments used, measurements made and indications of quantity expressed in units of measurement. Recital 2 of that directive says explicitly that the scope is not limited to any specific field of Community action, which is why the earlier reading limiting it to economic, public-health, safety and administrative purposes no longer matches the text. A size, weight or volume figure in a listing, in a catalogue, on a shelf-edge label or in marketing copy is an indication of quantity like the one on the pack. What the directive does not do is decide whether a quantity must be declared at all, or where; that is for the sector rules.

### Are there exceptions for air, sea and rail transport?

Yes, one. Article 2(b) says the directive does not affect the use in the field of air and sea transport and rail traffic of units, other than those it makes compulsory, which have been laid down in international conventions or agreements binding the Union or the Member States. The Danish SI order repeats the same exception for shipping, aviation and rail traffic. The exception is limited to the units those instruments lay down: it does not make non-metric labelling generally lawful for a transport operator, and everything else that operator states in a unit of measurement still follows Chapter I.

### What about equipment that was already in use before the rules came in?

Article 4 authorises units that are not or are no longer legal for products and equipment already on the market or in service on the date the directive was adopted, and for components and parts of products and equipment that are necessary to supplement or replace components or parts of those products and equipment. Legal units may nevertheless be required for the indicators of measuring instruments. Denmark writes the same rule with a fixed date, allowing non-prescribed units for goods and equipment placed on the market or taken into use before 1 July 1977 and for the loose parts and components that supplement or replace parts of them. None of this reaches new production, and none of it excuses a non-metric figure on a product placed on the market today.

### Who enforces the units rules in Denmark and what are the penalties?

The directive has no enforcement or penalty article; Article 7 leaves that to national law, and since 16 July 2021 national authorities act with the powers of Regulation (EU) 2019/1020, which lists the directive as point 6 of its Annex I. In Denmark the rules are in executive order nr. 866 of 11 May 2021 on the international system of units, SI, and other legal units, issued by Sikkerhedsstyrelsen under section 18(1) and section 23(3) of act nr. 1518 of 18 December 2018 on business promotion, whose section 18(1) then required the minister to make rules on metrology, including which units of measurement apply. That power has since moved: act nr. 782 of 4 May 2021 transferred metrology to the product act with effect from 1 July 2021, where the minister's rule-making power for units of measurement is now section 8a and units of measurement are product area nr. 19 of section 2(1). Section 7(1) of act nr. 782/2021 keeps rules made under chapter 8 of the business promotion act in force until they are repealed or replaced by rules made under the product act, which is why order nr. 866/2021 — issued seven weeks before the transfer took effect — still stands, and why section 18 of the current consolidation of the business promotion act (LBK nr. 230 of 29 February 2024) no longer contains a metrology power at all. So the two instruments are not two parallel regimes but a transition: the order is the substantive rule, the product act supplies the control authority, the powers and the penalties. The order fines breaches of the duty to use the prescribed units and of the predominance rule, and fines anyone who intentionally or through gross negligence states an SI unit so as to mislead. The product act names Erhvervsstyrelsen as the control authority, which may delegate metrology control, and gives it orders to warn, stop misleading marketing, remedy, stop sales, withdraw, recall or destroy, prohibitions, and orders to the owner of an instrument used for payment-based measurement. The SI order itself provides only for fines. The product act's imprisonment of up to 2 years in aggravating circumstances attaches to the offences listed in its section 37(1)(1) and (3) to (10) — in practice, for this product area, a breach of the act's own product requirements, a failure to give the control authority information or access, or a failure to comply with its decisions — and units of measurement are inside the product-area band of section 37(2). It does not attach to a breach of the SI order's own rules, and the points that rest on Article 4 and Article 5 of Regulation (EU) 2019/1020 cannot apply here, because the directive is not in the Article 4(5) list. Since January 2026 Sikkerhedsstyrelsen is the department Markedsovervågning of Erhvervsstyrelsen.

## What changed

- 2026-09-13 (guidance): **Guide rebuilt on the SPEC-62 model from the consolidated directive text** — The guide was rewritten from the consolidated text of 13 June 2020, Directive 2009/3/EC, Commission Directive (EU) 2019/1258, Regulation (EU) 2019/1020, the Danish SI order nr. 866/2021 and the Danish product act. Four statements in the earlier text are corrected: the scope is no longer the economic, public-health, safety and administrative purposes of the pre-2009 Article 2(a) but measuring instruments used, measurements made and indications of quantity expressed in units of measurement; supplementary indications are governed by the predominance rule and the character-size rule of Article 3(4) rather than by a general prominence test; the Danish authority is Erhvervsstyrelsen as control authority with Sikkerhedsstyrelsen as its department Markedsovervågning since January 2026, under the SI order and the product act, not Sikkerhedsstyrelsen in the abstract; and the guide now sets out the restricted Chapters II, III and IV, the air, sea and rail exception of Article 2(b) and the Article 4 grandfathering, none of which the earlier text mentioned.
- 2021-07-16 (applies): **Regulation (EU) 2019/1020 applies to the directive as Annex I legislation** — Directive 80/181/EEC is point 6 of Annex I to Regulation (EU) 2019/1020, which makes it Union harmonisation legislation for the purposes of that regulation, so national market surveillance authorities exercise its Article 14 powers and Article 16 measures for units of measurement. The directive is not in the Article 4(5) list, so the duty to have an economic operator established in the Union does not follow from it, and it is not in Annex II, so the Article 41 penalty duty does not reach it through the regulation.
- 2021-05-14 (applies): **Danish executive order nr. 866/2021 on the SI and other legal units in force** — The order replaces order nr. 618 of 13 May 2020 and implements the directive as amended through 2019/1258. It requires prescribed units when measuring instruments are used, measurements made and quantities indicated, keeps the shipping, aviation and rail exception, authorises supplementary indications with the SI figure predominant and the non-SI characters no larger, asks that the SI unit be stated clearly with writing rules in its Annex 2, allows non-prescribed units for goods and equipment placed on the market or taken into use before 1 July 1977, and fines breaches.
- 2020-06-13 (applies): **Member States apply the constant-based SI definitions** — The provisions transposing Commission Directive (EU) 2019/1258 apply from 13 June 2020 in every Member State, deliberately on one date so that the definitions are implemented uniformly; this is the date of the consolidated version of the directive in force today.
- 2019-08-13 (amendment): **Commission Directive (EU) 2019/1258 redefines the SI base units** — Section 1.1 of Chapter I of the Annex is replaced with the definitions adopted at the 26th meeting of the General Conference on Weights and Measures in 2018, which fix the seven base units by the numerical values of seven defining constants and keep the degree Celsius as the special name for the derived unit of temperature.
- 2010-01-01 (applies): **Member States apply the measures transposing Directive 2009/3/EC** — The transposition deadline was 31 December 2009 and the national measures apply from 1 January 2010, so from that date supplementary indications are authorised without an end date, the Chapter II units keep their status without a closing date, and the rewritten Article 2(a) governs the scope.
- 2009-05-27 (amendment): **Directive 2009/3/EC removes the end dates and clarifies the scope** — Article 1(b) is replaced so the Chapter II units stay legal without a closing date in the Member States that authorised them on 21 April 1973, Article 2(a) is replaced so the obligations relate to measuring instruments used, measurements made and indications of quantity expressed in units of measurement, Article 3(2) is replaced so supplementary indications are simply authorised, Article 6b adds a Commission reporting duty by 31 December 2019, the acre is deleted from Chapter II, and the SI derived unit tables of Chapter I are rewritten.
- 2000-02-09 (amendment): **Directive 1999/103/EC extends supplementary indications, inserts Article 6a and updates the Annex** — Replaces '31 December 1999' by '31 December 2009' in Article 3(2), extending the authorisation of supplementary indications by a further ten years so that Union exporters could keep marking products for third countries that do not accept metric-only marking. It inserts Article 6a, under which issues concerning implementation and in particular supplementary indications are to be examined further and measures adopted where necessary under the committee procedure of Article 18 of Council Directive 71/316/EEC. Directive 71/316/EEC was repealed by Directive 2009/34/EC, whose Article 20 provides that references to the repealed directive are construed as references to it and read in accordance with the correlation table in its Annex IV; that table makes Article 18(1) of Directive 71/316/EEC into Article 17(1) of Directive 2009/34/EC. The committee is therefore the Committee for Adjustment to Technical Progress of the Directives referred to in Article 16 of Directive 2009/34/EC, and it is the route by which Commission Directive (EU) 2019/1258 was adopted. One limit is worth knowing: the second paragraph of Article 16 of Directive 2009/34/EC excludes from that procedure the chapter of the Annex to the units directive that deals with imperial units of measurement, so the Commission cannot change Chapters II to IV this way — only the Council and Parliament can. And it amends the Annex in four places: the text under the table in Chapter I point 1.1.1 (the Celsius temperature definition), the definitions of the SI supplementary units radian and steradian following the table in point 1.2.1 (ISO 31-1:1992), the prefix table in point 1.3, which runs from yotta to yocto, and point 3 on the electronvolt and the unified atomic mass unit. Adopted on 24 January 2000 despite its 1999 number, in force on the day of publication, and to be transposed before 9 February 2001.
- 1989-11-30 (amendment): **Council Directive 89/617/EEC sets the closing dates for the imperial chapters** — Replaces points (b) and (c) of Article 1 with three points (b), (c) and (d), so that the Chapter II units stay legal until a date the Member States concerned fix, the Chapter III units until a date no later than 31 December 1994 and the Chapter IV units — a chapter this directive creates — until a date no later than 31 December 1999, in each case only in the Member States where they were authorised on 21 April 1973. In Article 3 it replaces '31 December 1989' by '31 December 1999' in paragraph 2, extending the authorisation of supplementary indications by ten years, and deletes paragraph 5. It updates the ISO 2955 reference in Article 5 from 1 March 1974 to 15 May 1983, and deletes the second subparagraph of Article 6. In the Annex it replaces Chapter II, deletes the fathom from Chapter III and adds Chapter IV. Member States had 24 months from notification, which took place on 30 November 1989.
- 1984-12-20 (amendment): **Council Directive 85/1/EEC redefines the metre and adds the millimetre of mercury and the barn** — Does three things. It replaces the definition of the unit of length in Chapter I point 1.1 with the 1983 definition — 'A metre is the length of the path travelled in a vacuum by light during 1/299 792 458 seconds' (Seventeenth CGPM (1983), Resolution 1). It adds two units to the specialised-field table of Chapter I point 4, the millimetre of mercury for blood pressure and the pressure of other body fluids (1 mm Hg = 133,322 Pa) and the barn for effective cross-sectional area (1 b = 10⁻²⁸ m²), and replaces the note so that the prefixes of point 1.3 may be used with the units of that table except the millimetre of mercury, the multiple of 10² ares being called a hectare. And it deletes the blood-pressure unit from Chapter II and replaces that chapter's note. Member States had to bring the measures into force on 1 July 1985.
- 1981-10-01 (applies): **National measures apply and Directive 71/354/EEC is repealed** — Member States had to adopt and publish the transposing laws before 1 July 1981 and apply them from 1 October 1981, the same date on which Directive 71/354/EEC on units of measurement was repealed.
- 1979-12-21 (in-force): **Council Directive 80/181/EEC enters into force** — Adopted on 20 December 1979 and published in OJ L 39 of 15 February 1980, the directive took effect on 21 December 1979 according to the dates EUR-Lex records, with a transposition deadline of 30 June 1981 and application from 1 October 1981.

## UoMD in plain terms

The Units of Measurement Directive (UoMD), formally Council Directive 80/181/EEC on the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC, decides which units may lawfully be used to express a quantity in the European Union. Article 1 names the legal units: those listed in Chapter I of the Annex, which is the International System of Units; those of Chapter II only in the Member States where they were authorised on 21 April 1973; and those of Chapters III and IV only in those same States and only until a date those States had to fix, no later than 31 December 1994 and 31 December 1999 (Art. 1). Article 2(a), as replaced by Directive 2009/3/EC, says what the obligation attaches to: measuring instruments used, measurements made and indications of quantity expressed in units of measurement. That wording is deliberately broad. Recital 2 of Directive 2009/3/EC explains that the scope is consistent with the internal-market objective of the Treaty and is not limited to any specific field of Community action, which is why the older formula about economic, public-health, safety and administrative purposes no longer describes the text.

The directive was adopted on 20 December 1979 and published in OJ L 39 of 15 February 1980; EUR-Lex records its entry into force and date of effect as 21 December 1979. Member States had to adopt and publish the implementing laws before 1 July 1981 and to apply them from 1 October 1981, the day Directive 71/354/EEC was repealed (Art. 6 and Art. 7(a)). Five acts have amended it since: Council Directive 85/1/EEC, Council Directive 89/617/EEC, Directive 1999/103/EC, Directive 2009/3/EC and Commission Directive (EU) 2019/1258. The last of them carried the 2018 redefinition of the SI base units into Union law, which is why the consolidated version in force today is dated 13 June 2020.

> **Official text**
> Read the directive on EUR-Lex: [consolidated version of 13 June 2020 (CELEX 01980L0181-20200613)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:01980L0181-20200613), or the [act as published in OJ L 39 (CELEX 31980L0181)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:31980L0181). The [document information page](https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:31980L0181) lists the dates, the five amending acts and the corrigenda.

## Scope

The directive regulates the unit, not the declaration. It does not say that a pack must carry a net quantity, nor where the figure has to sit; the sector rules do that. What it says is that when a quantity is expressed in a unit of measurement, the unit has to be a legal one (Art. 1 and Art. 2(a)). Because the obligation is written around instruments, measurements and indications rather than around a product surface or a business sector, it reaches the label, the packaging, the instructions, the spec sheet, the shelf-edge label, the listing and the marketing copy alike, and it reaches public administration, health and safety bodies and laboratories as much as manufacturers, importers and distributors.

Four carve-outs matter. First, the directive does not affect the use, in the field of air and sea transport and rail traffic, of units other than those it makes compulsory, where those units have been laid down in international conventions or agreements binding the Union or the Member States (Art. 2(b)). Second, units that are not or are no longer legal may still be used for products and equipment already on the market or in service on the date the directive was adopted, and for the components and parts needed to supplement or replace components or parts of those products and equipment, although legal units may be required for the indicators of measuring instruments (Art. 4). Third, the Chapter II units remain legal in the Member States that authorised them on 21 April 1973 (Art. 1(b)). Fourth, Member States may require measuring instruments to bear indications of quantity in a single legal unit (Art. 3(3)).

The chapters of the Annex are worth reading as a hierarchy. Chapter I is the general one and the only one that is legal everywhere. Chapter II is the narrow survival: the mile, yard, foot and inch for road traffic signs and distance and speed measurement, the pint for the dispense of draught beer and cider and for milk in returnable containers, and the troy ounce for transactions in precious metals; recital 1 of Directive 2009/3/EC identifies these as the exemptions applied by the United Kingdom and Ireland and explains that they were kept because their local character and the limited number of products meant they created no barrier to trade, while the acre was deleted because it was no longer used for land registration there. Article 1(b) attaches the exemption to Member States, so within the Union today it is Ireland that the chapter can still reach; the United Kingdom left the Union on 31 January 2020, and whatever status the pint, the mile and the troy ounce have there now is a matter of United Kingdom law and not of this directive. Chapters III and IV were transitional: sixteen imperial length, area, volume, mass and energy units in Chapter III and seven field-specific units in Chapter IV, the fathom for marine navigation, the pint and fluid ounce for beer, cider, waters, lemonades and fruit juices in returnable containers, the gill for spirit drinks, the ounce avoirdupois and the pound for goods sold loose in bulk and the therm for gas supply. Both chapters ran only until a date each Member State fixed under Article 1(c) and (d), which could not be later than 31 December 1994 and 31 December 1999.

## What you must do

### Use a Chapter I unit as the governing figure

Chapter I starts with the seven SI base units and their decimal multiples and submultiples. The base units are the second, the metre, the kilogram, the ampere, the kelvin, the mole and the candela (Annex, Chapter I, point 1.1). Point 1.1.1 keeps the degree Celsius as the special name and symbol of the SI derived unit of temperature, defined as the difference between two thermodynamic temperatures where the reference is 273,15 kelvin, and notes that an interval or difference of temperature may be expressed in either unit. Point 1.2 sets the general rule for SI derived units, which are algebraic expressions formed as products of powers of the base units with a numerical factor of 1, and lists the twenty-one derived units with special names and symbols: radian, steradian, hertz, newton, pascal, joule, watt, coulomb, volt, ohm, siemens, farad, weber, tesla, henry, lumen, lux, becquerel, gray, sievert and katal, with the volt-ampere and the var noted as special names for the unit of power (Annex, Chapter I, point 1.2.3).

Point 1.3 lists the twenty prefixes, from yotta at 10 to the power 24 down to yocto at 10 to the power minus 24, and three composition rules that are easy to get wrong: the names and symbols of the decimal multiples and submultiples of the unit of mass are formed by attaching prefixes to the word gram and their symbols to the symbol g; where a derived unit is written as a fraction, a prefix may be attached to units in the numerator, in the denominator or in both; and compound prefixes formed by juxtaposing several prefixes may not be used. Point 1.4 adds the three specially authorised names, the litre with the symbol l or L, the tonne and the bar. Point 2 covers units defined on the basis of SI units that are not decimal multiples of them, the revolution, the grade or gon, the degree, the minute and second of angle, and the minute, hour and day. Point 3 covers the two units whose values in SI are obtained experimentally, the electronvolt and the unified atomic mass unit. Point 4 lists the six units permitted in specialised fields only: the dioptre for the vergency of optical systems, the metric carat for the mass of precious stones, the are for the area of farmland and building land, the tex for the mass per unit length of textile yarns and threads, the millimetre of mercury for blood pressure and the pressure of other body fluids, and the barn for effective cross-sectional area, with a note that the prefixes may be used with all of them except the millimetre of mercury and that the multiple of 100 ares is called a hectare. Point 5 allows compound units formed by combining any of the units in Chapter I.

### The 2018 definitions of the base units

Since Commission Directive (EU) 2019/1258, the base units are defined by fixing the numerical values of seven defining constants rather than by artefacts or experiments. The second is fixed by the caesium frequency, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, at 9 192 631 770 hertz. The metre is fixed by the speed of light in vacuum at 299 792 458 metres per second. The kilogram is fixed by the Planck constant at 6,626 070 15 times 10 to the power minus 34 joule second. The ampere is fixed by the elementary charge at 1,602 176 634 times 10 to the power minus 19 coulomb. The kelvin is fixed by the Boltzmann constant at 1,380 649 times 10 to the power minus 23 joule per kelvin. The mole contains exactly 6,022 140 76 times 10 to the power 23 elementary entities, the Avogadro number. The candela is fixed by a luminous efficacy of 683 lumen per watt for monochromatic radiation at 540 terahertz. The General Conference on Weights and Measures adopted these definitions at its 26th meeting in 2018, effective internationally from 20 May 2019; the Commission directive carried them into the Annex, Member States had to transpose by 13 May 2020 and apply from 13 June 2020, and the application date was made uniform on purpose so the definitions took effect everywhere at once (Directive (EU) 2019/1258, recitals 3 to 7 and Art. 2). Nothing about the size of a kilogram or a metre changed; only the way they are anchored did.

### Supplementary indications

Article 3(1) defines a supplementary indication as one or more indications of quantity expressed in units not contained in Chapter I accompanying an indication of quantity expressed in a unit contained in that Chapter. Article 3(2), as replaced by Directive 2009/3/EC, authorises them outright; before that amendment the authorisation was due to expire on 31 December 2009, and the reason given for making it permanent was to avoid creating obstacles for Union undertakings exporting to third countries that require other units, with the added observation that supplementary indications could also allow new metric units developed internationally to be introduced gradually (Directive 2009/3/EC, recitals 3 and 6).

The conditions are exact. The indication expressed in a Chapter I unit must predominate, and in particular the indications expressed in units not listed in Chapter I must be expressed in characters no larger than those of the corresponding Chapter I indication (Art. 3(4)). Two consequences follow. A non-metric figure printed without the metric one beside it is not a supplementary indication at all and is not permitted. And an imperial figure set in larger or heavier type than the metric one breaks the rule even where both figures are present. Member States may additionally require that measuring instruments bear indications of quantity in a single legal unit (Art. 3(3)); Denmark has not taken that option, and its order repeats only the predominance and character-size rules and asks that the SI unit be indicated so that it is clear which unit is meant, offering writing rules in its Annex 2 (executive order nr. 866/2021, § 3).

### Denmark

Denmark implements the directive through executive order nr. 866 of 11 May 2021 on the international system of units, SI, and other legal units, issued by Sikkerhedsstyrelsen under section 18(1) and section 23(3) of act nr. 1518 of 18 December 2018 on business promotion, whose section 18(1) then required the minister to make rules on metrology, including which units of measurement apply. That power has since moved: act nr. 782 of 4 May 2021 transferred metrology to the product act with effect from 1 July 2021, where the minister's rule-making power for units of measurement is now section 8a and units of measurement are product area nr. 19 of section 2(1). Section 7(1) of act nr. 782/2021 keeps rules made under chapter 8 of the business promotion act in force until they are repealed or replaced by rules made under the product act, which is why order nr. 866/2021 — issued seven weeks before the transfer took effect — still stands, and why section 18 of the current consolidation of the business promotion act (LBK nr. 230 of 29 February 2024) no longer contains a metrology power at all. So the two instruments are not two parallel regimes but a transition: the order is the substantive rule, the product act supplies the control authority, the powers and the penalties. The order entered into force on 14 May 2021 and repealed order nr. 618 of 13 May 2020. Its footnote lists the directive and all five amending acts. Section 1 requires prescribed units, meaning the SI units of its Annex 1, when measuring instruments are used, measurements made and quantities indicated in units of measurement, and section 1(3) points to the conversion factors of Annex 3 for older Danish units. Section 2 repeats the exception for shipping, aviation and rail traffic. Section 3 authorises supplementary indications, requires the SI figure to be prominent and the non-SI characters to be at most the same size, and asks that the SI unit be stated unambiguously. Section 4 allows non-prescribed units for goods and equipment already placed on the market or taken into use before 1 July 1977 and for the loose parts and components of such goods. Section 5 fines breaches of sections 1(1), 1(3) and 3(3) and fines anyone who intentionally or through gross negligence states an SI unit contrary to section 3(4) in order to mislead, with corporate criminal liability under chapter 5 of the criminal code.

One detail is worth noticing: Annex 1 of the Danish order reproduces Chapter I of the directive and nothing else. The mile, pint and troy ounce of Chapter II are not Danish legal units, and neither are the imperial units of the expired Chapters III and IV; in Denmark they can only ever appear as supplementary indications beside a predominant SI figure.

## Enforcement and penalties

Unlike the CE-marking directives, Directive 80/181/EEC contains no market surveillance chapter, no safeguard procedure and no penalty article. Article 7 requires Member States to adopt, publish and apply the necessary laws, regulations and administrative provisions, to inform the Commission of them, and to give the Commission sight of drafts in the field in good time for it to comment. Enforcement therefore runs on national law, supported since 16 July 2021 by Regulation (EU) 2019/1020: the directive is point 6 of Annex I to that regulation, which makes it Union harmonisation legislation for the regulation's purposes, so the national authorities hold the Article 14 powers to require information and documents, carry out checks and enter premises, and the Article 16 measures to require corrective action, prevent a product being made available, order withdrawal, recall or destruction, set prior conditions and warn end users. Two negatives matter as much as the positive: the directive is absent from the Article 4(5) list, so the duty to have an economic operator established in the Union does not flow from it, and it is absent from Annex II, so the Article 41 duty on Member States to lay down penalties does not reach it through the regulation either.

In Denmark the two instruments are not two parallel regimes but a transition: the order is the substantive rule, the product act supplies the control authority, the powers and the penalties. Executive order nr. 866/2021 fines breaches of the legal-unit duty and of the predominance rule, and adds a separate fine for stating an SI unit misleadingly. The product act (lov om produkter og markedsovervågning, LBK nr. 22 of 8 January 2026) lists SI and other units of measurement covered by the Council directive on units of measurement as point 19 of section 2(1), empowers the minister to make rules on measurement technique and the use of units for the metrology areas in points 13 to 19 (§ 8 a), names Erhvervsstyrelsen as the control authority (§ 9) and allows it to authorise another public authority or a public or private undertaking to carry out metrology control (§ 9 a). Its toolkit runs from warnings and orders to stop misleading marketing, remedy, stop sales, withdraw, recall or destroy (§ 14), through prohibitions on placing on the market, making available, supplying or putting into use, with destruction where a prohibition is ignored (§ 16), to orders to the owner of an instrument used where payment is based on the measurement (§ 16 a). Section 37 fines the party that fails to comply with those decisions and raises the penalty to imprisonment of up to 2 years in aggravating circumstances for the product areas in points 13 to 43, which include units of measurement; companies can be held criminally liable. Since January 2026 Sikkerhedsstyrelsen is the department Markedsovervågning of Erhvervsstyrelsen and carries out the same tasks.

## How Conphora helps

Conphora monitors the Units of Measurement Directive, its amending acts and the Danish SI order, and maps your products against them: it finds every place a quantity is expressed, on the pack, in the manual, in the spec sheet and in the listing, checks that the governing figure is a Chapter I unit, flags a non-metric value that stands alone or that is set as large as the metric one, and warns when a specialised unit such as the metric carat, the tex or the millimetre of mercury is used outside its field. The platform keeps the unit question aligned with the sector rules that decide whether a quantity must be declared at all, and alerts you when the Annex, the Danish order or the enforcement setup changes.

[See how Conphora works](/how-it-works) · [See plans and pricing](/pricing)

## Sources

- [Consolidated text of Council Directive 80/181/EEC on units of measurement, version of 13 June 2020 (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:01980L0181-20200613)
- [Council Directive 80/181/EEC as published in OJ L 39, 15 February 1980 (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:31980L0181)
- [Document information, dates, corrigenda and amending acts for CELEX 31980L0181 (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:31980L0181)
- [Directive 2009/3/EC amending Directive 80/181/EEC (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0003)
- [Commission Directive (EU) 2019/1258 on the definitions of the SI base units (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32019L1258)
- [Directive 2009/34/EC on common provisions for measuring instruments and methods of metrological control, which replaced Directive 71/316/EEC (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0034)
- [Regulation (EU) 2019/1020 on market surveillance and compliance of products (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32019R1020)
- [Units of measurement in the EU (European Commission, DG GROW)](https://single-market-economy.ec.europa.eu/single-market/goods/building-blocks/legal-metrology/units-measurement-eu_en)
- [Legal metrology (European Commission, DG GROW)](https://single-market-economy.ec.europa.eu/single-market/goods/building-blocks/legal-metrology_en)
- [Bekendtgørelse nr. 866 af 11. maj 2021 om det internationale enhedssystem, SI, og andre lovlige enheder (Retsinformation)](https://www.retsinformation.dk/eli/lta/2021/866)
- [Bekendtgørelse nr. 618 af 13. maj 2020 om det internationale enhedssystem, SI, og andre lovlige enheder (Retsinformation)](https://www.retsinformation.dk/eli/lta/2020/618)
- [Bekendtgørelse af lov om produkter og markedsovervågning, LBK nr. 22 af 8. januar 2026 (Retsinformation)](https://www.retsinformation.dk/eli/lta/2026/22)
- [Regler og bekendtgørelser for måling og vægt (Sikkerhedsstyrelsen)](https://www.sik.dk/erhverv/produkter/maaling-og-vaegt-metrologi/love-og-regler-0/regler-og-bekendtgoerelser-maaling-og-vaegt)
- [Sikkerhedsstyrelsen, en del af Erhvervsstyrelsen from January 2026 (Erhvervsstyrelsen)](https://erhvervsstyrelsen.dk/sikkerhedsstyrelsen-en-del-af-erhvervsstyrelsen)

*This guide is for general information and is not legal advice.*

## Sources

- [Consolidated text of Council Directive 80/181/EEC on units of measurement, version of 13 June 2020 (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:01980L0181-20200613)
- [Council Directive 80/181/EEC as published in OJ L 39, 15 February 1980 (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:31980L0181)
- [Document information, dates, corrigenda and amending acts for CELEX 31980L0181 (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:31980L0181)
- [Directive 2009/3/EC amending Directive 80/181/EEC, which made supplementary indications and the Chapter II units open-ended (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0003)
- [Commission Directive (EU) 2019/1258 adapting the Annex to the 2018 definitions of the SI base units (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32019L1258)
- [Directive 2009/34/EC on common provisions for measuring instruments and methods of metrological control, which replaced Directive 71/316/EEC and supplies the committee referred to in Article 6a (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0034)
- [Regulation (EU) 2019/1020 on market surveillance and compliance of products, whose Annex I lists the directive as point 6 (EUR-Lex)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32019R1020)
- [Units of measurement in the EU (European Commission, DG GROW)](https://single-market-economy.ec.europa.eu/single-market/goods/building-blocks/legal-metrology/units-measurement-eu_en)
- [Legal metrology (European Commission, DG GROW)](https://single-market-economy.ec.europa.eu/single-market/goods/building-blocks/legal-metrology_en)
- [Bekendtgørelse nr. 866 af 11. maj 2021 om det internationale enhedssystem, SI, og andre lovlige enheder (Retsinformation)](https://www.retsinformation.dk/eli/lta/2021/866)
- [Bekendtgørelse nr. 618 af 13. maj 2020 om det internationale enhedssystem, SI, og andre lovlige enheder, repealed on 14 May 2021 (Retsinformation)](https://www.retsinformation.dk/eli/lta/2020/618)
- [Bekendtgørelse af lov om produkter og markedsovervågning, LBK nr. 22 af 8. januar 2026 (Retsinformation)](https://www.retsinformation.dk/eli/lta/2026/22)
- [Regler og bekendtgørelser for måling og vægt (Sikkerhedsstyrelsen)](https://www.sik.dk/erhverv/produkter/maaling-og-vaegt-metrologi/love-og-regler-0/regler-og-bekendtgoerelser-maaling-og-vaegt)
- [Sikkerhedsstyrelsen, en del af Erhvervsstyrelsen from January 2026 (Erhvervsstyrelsen)](https://erhvervsstyrelsen.dk/sikkerhedsstyrelsen-en-del-af-erhvervsstyrelsen)

_Reviewed 2026-09-24 by Conphora compliance team_