Calculate maximum permissible errors (MPE) for weighing scales per OIML R 76 accuracy class, capacity and number of divisions.
Class III: 100–10 000 divisions
Enter scale capacity and number of divisions to calculate tolerances.
Maximum Permissible Errors per OIML R 76-1 for initial verification. In-service MPE is double these values. Always calibrate with NATA-traceable weights.
OIML R 76 is the International Recommendation for non-automatic weighing instruments. In NZ, the Weights and Measures Act 1987 and the Measurement Standards Act 1992 require trade-used scales to meet accuracy class III requirements and be verified by an Inspector of Weights and Measures. OIML R 76 defines the test procedures and maximum permissible errors (MPE).
MPE is the largest acceptable difference between the scale reading and the true weight. For Class III scales (used in most trade applications), the MPE at zero is ±0.5e (where e is the scale interval), increasing to ±1.5e at full load. During initial verification (new scale), these values apply. In-service MPE is double the initial values.
In NZ, scales used for trade (selling goods by weight) must be verified by an Inspector of Weights and Measures before first use and periodically thereafter. The reverification period depends on scale type and use. Scales in high-use environments (supermarkets, butcheries) may be checked annually. NATA-accredited laboratories can perform calibration, but only Inspector verification satisfies the legal requirement.