Calibration is the legally required testing of a measuring instrument for compliance with the underlying legal regulations, in particular the calibration error limits according to the Weights and Measures Act. In Germany, calibration is a sovereign task according to the Weights and Measures Act.
Until 2014, the main stamp confirmed the expected compliance for the validity period of the calibration. From 2015, this was replaced in the EU (and EFTA) by a manufacturer’s declaration of conformity and by affixing the "additional metrology marking."
The term calibration is often mistakenly used for calibration.
The testing of measuring instruments that do not meet legal requirements or for which there is no calibration requirement under the Weights and Measures Act constitutes a calibration.
An internal calibration is a calibration in which all measuring instruments are standardized to a company-internal or organization-internal standard.
A traceable calibration is a calibration whose reference is a national standard (e.g. a measuring device/measuring setup of the PTB), the measurement results obtained are consequently traceable to this national standard.
Traceable measuring instruments are often also referred to as reference measuring instruments.
The advantage of measuring instruments traceable to national (and thus usually also international) standards is the worldwide comparability of the measurement results.
