NIST calibrates individual weights or sets in the range of 1 mg to 50 kg in decimal subdivisions. Weights must be of one piece construction, with no adjustment cavity, material, and surface finish comparable to ASTM Type I, classes 00, 0, 1, 2, and OIML E1, E2, and F1. NIST also calibrates large mass standards larger than 50 kg to 28 000 kg if the design, material, and surface finish are compatible with the intended usage. For these large mass standards, an adjustment with reference to a nominal or desired value can be included as a part of the calibration procedure.
All mass calibrations are traceable to the SI through the following traceability chain: