Test equipment weight determination


Example: A balance has a maximum capacity max. = 1,000 g and a scale interval d = 10 mg. The operating instructions specify a nominal value of 1 kg for an external calibration weight. According to A.1. the balance has a number of steps n = 100,000.

From A.2., the required MPE for the nominal value of 1 kg is between 5 mg and 10 mg. The MPE class F1 meets this requirement (+/-5 mg).

B.2. specifies the following test weights: 250 g, 500 g, 750 g and 1 kg. According to OIML R111 the following 4 test weights of class F1 are defined: 50 g, 200 g, 500 g, 1 kg.



Determination of the correct MPE class (tolerances) for the test weights

  1. Determine the number of steps n (number of division values) using the maximum load max. and the division value d (smallest readable digit step) of the weighing range (measuring range).

    Number of steps n = Max. load / pitch d

  2. Determine the MPE class of the test weight using the required MPE.

Weighing ranges (measuring ranges) Error limit of the test weight, depending on the safety requirement
n = 100.000 0,5 d and 1 d
100.000between 1 d und 2 d
n > 500.000 less than 3 d

To do this, select a nominal value equal to or close to the maximum load of the weighing range (measuring range).
However, this nominal value should always be greater than 80 % of the maximum load Max.

Small upward and downward roundings are permissible. In case of doubt, however, always use the next smaller error limit.



Determination of the required nominal values (weight sizes)

  1. Minimum check:
    You can perform most metrological tests for the weighing range with only one test weight (nominal value). The nominal value of the external calibration weight is often used for this purpose (see the operating instructions or operating software for your scale). However, this nominal value should always be greater than 80 % of the maximum load Max.

  2. Complete review:
    With this method you check the weighing range (measuring range) for the maximum possible requirements. The following 4 test loads are required: 25% / 50% / 75%/ 100% (or min. 80%) of the maximum load Max. load

    The test load 100% (or min 80%) should consist of one weight, i.e., should not be a combination of several test weights.


If you have any questions, we will be happy to advise you on selecting the test weights required. We support you in determining the test sequence and give you recommendations for the required documentation of your test results and their evaluation.




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