National measurement standards / National Metrology Institute

Metrosert is the National Metrology Institute of Estonia. We maintain and develop Estonian national measurement standards for length, mass, temperature and electrical quantities. The quality of numerous Estonian products and services is based on our measuring capability.



The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 x 10–34 when expressed in the unit J s, which is equal to kg m2 s–1, where the metre and the second are defined in terms of c and ΔνCs.

The Estonian National Laboratory for Mass realizes the scale of mass in the range from 1 mg to 50 kg using a group of 1 kg standard weights and highly accurate automated mass comparators. The 1 kg standard weights are calibrated by the International Bureau of Weights and Measures (BIPM) and the German National Metrology Institute (PTB).

The National Laboratory for Mass calibrates OIML Recommendation R 111-1 compliant weights in the accuracy range  E2 to F1 with an expanded measurement uncertainty of 2 μg to 15 mg.


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