A Guide to Trade Approved Balances and Scales

What is a trade approved balance?

To ensure transparency and fairness of commercial transactions, businesses which offer the sale of goods by weight must use balances which are approved for use in trade. Such balances are rigorously tested to a specific standard to ensure the balance weighs accurately. The legal requirements for the testing vary slightly depending on the country or state, but guidance can be found from organisations such as The International Organisation of Legal Metrology (OIML), National Type Evaluation Program (NTEP) and the National Measurement Institute (NMI).

Who requires a trade approved balance?

Businesses that sell products with a price that is directly determined by the product weight must use trade approved scales. Examples of products sold in this way include food, fuel, alcohol, precious metals and jewels. However, note that trade approved balances are not required to weigh individual components which are then mixed together to produce a finished product. A trade approved balance would only be required at the end of the process, if the product is to be sold by weight. It is illegal to sell products or produce by weight without the use of a trade approved balance.

Trade approval gives confidence to the buyer, and seller, that all transactions will be fair and equitable and helps to uphold a trader’s reputation.  For example, in the trading of precious metal it is imperative that the balance weighs accurately otherwise one party in the transaction could suffer significant financial loss.

Industries using trade approved scales. Enquire online for legal for trade scales.

The Non-Automatic Weighing Instruments Directive (NAWI) outlines six applications where trade approved scales must be used:


  • To determine the mass of produce for commercial transactions (e.g. weighing meat in a butcher shop).
  • To determine the price on the basis of mass for the purposes of direct sales to the public and for the production of pre-packages (e.g. balances used to make up pre-weighed non-predetermined quantities).


  • In circumstances where the mass is used to calculate a tax, tariff, penalty, or other type of payment or fee (e.g. transportation of goods, waste disposal, postal services).
  • Where mass must be determined for the application of regulations or law (e.g. to check compliance with statutory weight restrictions)


  • Where mass determination is conducted in a medical setting for the purposes of monitoring, diagnostic testing or medical treatment of a patient.
  • Where the mass is used to prepare prescription medication within a pharmacy, or for the determination of mass in analyses performed within pharmaceutical or medical laboratories.

How do you identify if a balance is trade approved?

How to identify legal for trade scales

To achieve the trade approval the balance must have successfully passed all the required tests, as set out by the legislation within that country or state. Balances which carry trade approval will have been tested by an approved independent qualifier.

Trade approval will typically be denoted on the label of a balance. This is generally an M symbol and there may also be a class mark. The M symbol is black, though older models may feature a green M symbol. Trade approved balances may also be known as; legal for trade scales, trade stamped, trade approved scales, verified, Class III, EC stamped, and M Class approved.

The class is indicative of the accuracy of the balance- Class I / Class II trade approved balances are suitable for applications which require high accuracy, such as pharmaceutical use. Class III balances are more suited to regular weighing tasks such as within retail or industrial applications. It is important to select the most appropriate class for the application, using an unsuitable class may be considered a violation of the law.

Maintaining trade approved scales

In addition to annual servicing, it is imperative that trade approved balances are well maintained and monitored to ensure continued performance. Environmental conditions, such as temperature changes, air currents, direct sunlight and vibrations can adversely affect the operation and the accurate weighing capability of the balance. Therefore, the balance must be tested at regular intervals to ensure there is no deterioration. Businesses which require the use of legal for trade balances may be subject to spot checks. Inspectors have the right to visit locations at any time to check that equipment is compliant with the guidelines and have the authority to issue penalties in the event of non-conformance.

Trade approved balances from Precisa

trade approved scales from Precisa. The Series 520 are legal for trade scales.

The Precisa 520 Series analytical and precision balances are trade approved. The Series 520 balances contain the innovative PHASTbloc™ (Precisa Hybrid Advanced Sensor Technology). This advanced weighing technology is the culmination of over 40 years of knowledge and experience and unites the benefits of a conventional weighing cell and monolithic design. This enables the efficient maintenance and repair of a weighing cell instead of replacing it – sustainability in practice. Advanced materials, Swiss engineering and unique manufacturing methods lift quality and performance to new heights.

To find out more about the trade approved Precisa 520 Series balances please contact us and a member of our team will be in touch.