NAWI - Directive 2014/31/EU

What NAWI is and why it matters

The Non-Automatic Weighing Instruments Directive (NAWI) — formally Directive 2014/31/EU on the harmonisation of the laws of the Member States relating to the making available on the market of non-automatic weighing instruments — is the EU’s legal-metrology law for scales that need an operator. A weighing instrument is “non-automatic” when it requires the intervention of an operator during the weighing process: someone places the load, reads the result, or otherwise acts before a result is obtained. Retail counter scales, platform scales, balances and many industrial scales fall into this category whenever a person is part of the weighing operation.

NAWI matters because it does not regulate weighing instruments in general — it regulates them when they are put to uses where the accuracy of the measurement has legal or economic consequences. If a scale is used to determine a price, settle a transaction, dispense a medicine, or produce a figure that a court or a public authority relies on, the law cares whether that scale is correct. NAWI sets the essential requirements, the accuracy classes, and the conformity-assessment routes that give buyers and authorities confidence that a regulated scale measures what it claims to.

📄 Official text: Directive 2014/31/EU on non-automatic weighing instruments — on EUR-Lex →

Who NAWI applies to

NAWI applies across the supply chain, and the duties scale with each actor’s role:

Manufacturers — anyone who makes a non-automatic weighing instrument, or has it made and markets it under their own name or trademark. They carry the heaviest obligations: ensuring the instrument is designed and made to meet the essential requirements, running the conformity assessment, drawing up technical documentation and the EU declaration of conformity, and applying the markings.
Authorised representatives — a person established in the EU appointed by the manufacturer in writing to carry out defined tasks on their behalf.
Importers — businesses bringing instruments from outside the EU onto the Union market. They must verify the manufacturer has done the conformity assessment, that the documentation exists and that the markings are in place, and they add their own identification.
Distributors — wholesalers and retailers who must act with due care, check that the CE marking, the supplementary metrology marking and the required documents are present, and not make available instruments they know or should presume to be non-compliant.

The decisive point under NAWI is intended use. The Directive distinguishes instruments intended for the regulated, legal-metrology applications — where the full conformity regime applies — from instruments intended for uses outside that scope, which fall under other legislation rather than NAWI’s metrological controls.

Regulated uses

NAWI’s metrological requirements apply when a non-automatic weighing instrument is used for one of the defined regulated purposes, in particular:

Determination of mass for commercial transactions — weighing goods that are bought and sold by weight.
Determination of mass for calculating a toll, tariff, tax, bonus, penalty, remuneration, indemnity or similar payment.
Determination of mass in the application of laws or regulations, and for expert opinions given in court proceedings.
Determination of mass in medical practice for weighing patients for monitoring, diagnosis and treatment.
Determination of mass in making up medicines on prescription in a pharmacy, and in analyses carried out in medical and pharmaceutical laboratories.
Determination of price on the basis of mass for direct sale to the public, and for the make-up of pre-packages.

When an instrument is intended for any of these uses, the full NAWI regime — essential requirements, accuracy classes and conformity assessment by the appropriate route — applies before it can be placed on the market.

Accuracy classes

NAWI defines four accuracy classes that set how precise an instrument must be for its intended use:

Class I — special accuracy (the most demanding, e.g. precision laboratory balances).
Class II — high accuracy (e.g. weighing of precious metals and stones, certain laboratory work).
Class III — medium accuracy (the common class for commercial and retail weighing).
Class IIII — ordinary accuracy (the least demanding, e.g. weighing of building materials).

Each class carries defined limits on the maximum permissible errors at verification and in service, and is linked to the instrument’s number of verification scale intervals and the value of the verification scale interval. Choosing the correct class for the intended application is part of getting the conformity assessment right.

Core requirements

Essential requirements and technical documentation

A regulated non-automatic weighing instrument must meet the essential metrological and technical requirements set out in the Directive — covering accuracy, suitability for the intended use, reliability, and resistance to disturbances — and must perform within the maximum permissible errors for its accuracy class. To demonstrate this, the manufacturer prepares technical documentation describing the design, manufacture and operation of the instrument and showing how it meets the essential requirements. This documentation must be kept available for the market surveillance authorities for the retention period and produced on request. Where harmonised standards exist, conformity with them gives a presumption of conformity with the corresponding essential requirements.

Conformity assessment and notified bodies

NAWI’s conformity assessment is built on modules. For regulated instruments, the manufacturer chooses a route appropriate to the product, and in most cases a notified body — an independent conformity-assessment body designated by a Member State — is involved. The typical routes combine an examination of the type or design with verification of production:

Module B (EU-type examination) combined with Module D, F or others for the production phase; or
Module G (conformity based on unit verification), where each individual instrument is examined and verified by a notified body.

For Class III and Class IIII instruments that do not use electronic devices and whose load-measuring device does not use a spring to balance the load, a route based on internal production control plus inspection (no type examination) can also be available. The result of a successful assessment is the EU declaration of conformity, in which the manufacturer takes sole responsibility that the instrument meets the requirements.

CE marking and the supplementary metrology marking

A compliant regulated instrument carries a distinctive set of markings. In addition to the CE marking, NAWI requires the supplementary metrology marking — the letter “M” together with the last two digits of the year it was applied, enclosed in a rectangle. The CE marking and the supplementary metrology marking are followed by the identification number of the notified body involved in the production-control phase. In practice the marking is often shown as a green sticker bearing the “M” — the green metrology label that identifies a verified, regulated instrument. These markings must be affixed before the instrument is placed on the market, be visible, legible and indelible, and signal that the instrument has passed conformity assessment for its regulated use.

Verification and putting into use

Conformity assessment establishes that an instrument type and unit are correct when placed on the market. Beyond that, instruments in regulated use are subject to national verification and metrological control arrangements, including periodic re-verification, so that an instrument remains accurate throughout its working life. Putting a regulated instrument into service for one of the defined uses, and keeping it in service, depends on it being and remaining verified.

Obligations by role

Manufacturers — design and make instruments to the essential requirements, select the accuracy class, run the conformity assessment with a notified body where required, hold the technical documentation, draw up the EU declaration of conformity, and apply the CE marking and the supplementary “M” metrology marking.
Authorised representatives — perform the tasks set out in their written mandate, including keeping documentation available to authorities.
Importers — verify the manufacturer has carried out conformity assessment, that the markings and documentation are present, add their own identification, and refuse non-compliant instruments.
Distributors — check that the CE and “M” markings and the accompanying documents are present before making an instrument available, and stop supply of instruments they believe to be non-compliant.

Enforcement

NAWI is enforced through the EU’s market-surveillance framework, with each Member State designating competent authorities for legal metrology. In Denmark, the Danish Safety Technology Authority (Sikkerhedsstyrelsen) is responsible for legal metrology, including the verification and market surveillance of weighing instruments used for regulated purposes. Authorities can require corrective action, restrict or prohibit the making available of non-compliant instruments, order withdrawal or recall, and act against incorrectly affixed markings.

Because NAWI is a directive, the obligations are given effect through national law in each Member State, but the essential requirements, accuracy classes and marking rules are harmonised across the Union, so an instrument lawfully placed on the market under NAWI can be made available throughout the EU. The qualitative reality for a manufacturer is that a missing or wrongly applied “M” marking, or an instrument used for a regulated purpose without verification, can stop sales and trigger market-surveillance action.

Getting compliant

Confirm whether your instrument is non-automatic and intended for one of NAWI’s regulated uses.
Determine the correct accuracy class (I, II, III or IIII) for the intended application.
Design and manufacture to the essential requirements, using harmonised standards where available.
Choose the appropriate conformity-assessment module and engage a notified body where required.
Compile and retain the technical documentation.
Draw up the EU declaration of conformity.
Affix the CE marking, the supplementary “M” metrology marking and the notified body number (the green metrology label).
Ensure instruments in regulated use are verified and re-verified under national metrological control.

How Conphora helps

Conphora monitors NAWI and maps your weighing instruments against its requirements, flagging gaps in accuracy class, conformity assessment, the EU declaration of conformity and the CE and “M” metrology markings before they become enforcement problems. The platform helps you generate and keep the right documentation, and alerts you when obligations change so your compliance stays current.

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Sources and further reading

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

Last updated: 12 June 2026