Frequently Asked Questions on Weights and Measures

The Weights and Measures Office (WMO) ensures that a uniform and accurate system of weights and measures is used in Singapore. With the system, consumers and traders are assured that they get what they pay for when buying goods that are weighed, measured or pre-packed. It also provides a correct measurement for excise tax computation for the Government.

The Weights and Measures Act ensures fair trading and penalizes traders for short-weights and measures. It enables WMO to enforce controls on weighing and measuring instruments used for trade, the net contents of pre-packaged goods as well as prevent unfair trading due to short-weights or measures.

WMO performs the following functions:

• Designating Authorised Verifiers for weighing and measuring instruments for trade use.

• Registering pattern of approved weighing and measuring instruments.

• Verifying (for accuracy) and stamping/sealing (to indicate approval and prevent tampering) all new or repaired weighing and measuring instruments for trade use.

• Inspecting such instruments for trade use for inaccuracies and tampering.

• Inspecting pre-packaged goods or goods sold by weight or measure for short-weight or measure.

• Investigating complaints pertaining to weights and measures matters from consumers or traders.

Your weighing or measuring instrument needs to be verified before it can be used for trade. Contact an Authorised Verifier (AV) to make arrangements to have your weighing or measuring instrument verified/stamped. A list of the AVs can be found at List of Authorised Verifiers of Weighing and Measuring Instruments.

The pattern of a weighing and measuring instrument refers to the design of an instrument with all components affecting its measurement properties suitably specified. Such instruments must show proof that they have undergone various tests and are in compliance with the relevant international standards. This is to ensure that the instruments can maintain their accuracy under different climatic and operating conditions.

By registering the pattern of the weighing and measuring instrument, it ensures that no substandard design of weighing and measuring instruments for trade use are used in Singapore.

This is to ensure that new or repaired weighing or measuring instruments meet the required maximum permissible error (MPE) before they can be used for trade. Consumers should look out for a verification seal and the ACCURACY Label as proof that they are fit for trade use. If the instrument is subsequently repaired, it should be adjusted for accuracy and verified following the repair.

An applicant wishing to seek approval and registration for a weighing or measuring instrument for trade use has to submit the following documents to WMO via the link here.

• OIML Certificate of Approval or Pattern Evaluation Certificate – to attest that the pattern of the weighing or measuring instrument is suitable for trade use.

• Test Report – attached together with the pattern approval certificate.

• Circuit Diagram with key components part list.

• Photographs – one external view, one with rating label and one internal view with key components.

• Diagrams and/or photographs of the weights and measures sealing provision

• User’s Instruction Manual with safety and calibration/adjustment instructions.

Only registered weighing and measuring instruments are allowed to be used for trade purposes in Singapore.

Depending on the availability/ completeness of documents provided, registration generally takes one month.

You are required to send your weighing or measuring instrument for re-verification minimally every year, or whenever the instrument is not working properly. A verification seal and ACCURACY Label would be affixed on the verified instrument. The ACCURACY Label is valid for a period of 12 months immediately following the month in which it is affixed.

Please note that it is an offence to use instruments with invalid ACCURACY Label, and/ or if the verification seal on the instrument is found to be tampered with. If the verification seal is found broken, you are required to send your instruments for reverification immediately.

Only the AVs are allowed to break the seal for the purpose of carrying out servicing and adjusting the pump.

However, the same pump cannot be used for trade unless it is locked. It must be kept locked until it has been verified accurate by the AV. This ensures that the instrument remains accurate and assures customers that it has not been tampered with.

If the pump is found accurate during verification, all adjustable parts of the pump will be sealed during the stamping of the pump. Thereafter, the pump can be used for trade.

You can file a report with the WMO through this online form. Please provide the following information:

• Date and time of incident

• Location of incident

• Product involved

• Quantity purchased

• Cost of product

• Receipt or invoice of the transaction if available

• Complainant’s particulars, including contact number

You may visit the National Metrology Centre's website at https://www.a-star.edu.sg/nmc for calibration services.

You may also visit https://www.sac-accreditation.gov.sg/ and search for a list of accredited organisations for calibration services.

For more enquiries, please contact us via our Contact Us page.