The frequency of testing required in between depends on the accuracy that you require, the environmental conditions and the associated risks during measurements. Higher accuracy requires more frequent testing. However, JET scales feature internal weight and FACT technology, which adjusts the scale automatically. When using FACT, the amount of testing can typically be reduced. Contact us for precise advice on testing balance and scale.

To qualify for "Legal for Trade", there are many extra requirements that a scale must fulfill over and above the requirements of a regular scale. For example, the additional software adaptations necessary will require extra investment for the manufacturer, adding to the price of the scale. The extensive conformity assessment that every legal-for-trade scale undergoes, and the required associated documentation for the approval, also contribute to the additional cost.

A calibration performed by an authorized service technician is always recommended to ensure passing the legal verification by Weight & Measures officers.

Through normal use, the performance of a weighing instrument will change over time. Calibrating a scale or balance once per year by an authorized service technician is always a good idea to maintain a documented record of its performance.

METTLER TOLEDO balances and scales are all produced to consistently high-quality standards. 

A legal-for-trade weighing instrument is not necessarily better than a regular one. It will depend on the accuracy of the instrument and its maintenance. A legal-for-trade instrument, however, ensures the fulfillment of minimum accuracy requirements and is subject to periodical inspections by Weight & Measures authorities. These are the reasons for the mandatory use of legal-for-trade weighing instruments for commercial transactions to protect consumers and ensure fair trade.

An “approved” or “verified” balance or scale is a weighing instrument which has been tested and certified by a competent authority to meet specific accuracy and reliability requirements for legally relevant applications including trade, safety, health, and environment.

Colloquially the term “legal-for-trade” associated to a scale or balance is expressed with the meaning of an approved weighing instrument used for trade, i.e. for commercial transactions.

d – actual weighing instrument interval - is the smallest division that a balance or scale can display.

e - verification weighing instrument interval - is the smallest interval on a balance or scale that is allowed to be used in a business transaction.

For example, a scale has d = 0.001 g, providing weight results to three decimal places. In the case that e=d, the scale can be used in business transactions measuring weight to three decimal places (0.001 g). In the case that e = 10d, the scale can only be used in business transactions measuring weight to 10 x 0.001 g = 0.01 g.

When the e value of the scale is greater than the d value (see previous question), the digit(s) in the weight result that cannot be included in a business transaction are shown in brackets.

A weighing instrument with d =0.01 g can´t weigh a total mass of 0.01 g accurately. Every mass measurement made on a balance or scale has a degree of uncertainty. When the item being weighed is very small, the error due to the measurement uncertainty becomes large compared to the mass of the item. Every balance has a point below which the uncertainty is so high that the weight results cannot be deemed to be accurate. This point is known as the minimum capacity. It is the smallest weight that you can weigh on your balance or scale with acceptable accuracy. This value is mandatory for a legal-for-trade weighing instrument. For a regular weighing instrument, the service technician can determine during calibration the minimum capacity required by customer´s requirements. If the customer requires a higher degree of accuracy, the minimum capacity must be increased (this reduces the level of uncertainty).

Contact your local METTLER TOLEDO representative to get a direct and personalized recommendation. You can also check your local Weights and Measures authority, or contact your country's Trading Standards office. They can help you determine if you need a legal-for-trade balance or scale. The OIML recommendation R76 or in the US, the NIST Handbook 44, provide guidance.