Calibration, according to the International Vocabulary of Terms in Legal Metrology (VIM), is a series of operations determining, in specified conditions, the relation between the values indicated by the measuring instrument or measuring unit or the values represented by the reference material and specified values represented by standards of mass.

Calibration is a voluntary act, ensuring the use of adequate measuring instruments whose indication and measurement uncertainty are known and guarantee measurement retraceability - reference to National Standards of Mass.

Maintaining measurement retraceability conditions uniqueness of measurements results and their reciprocal comparisons. Calibration of measuring devices is conducted by competent laboratories. The best acknowledgement of laboratory competence is its accreditation.

Users of measuring instruments conducting measurements in the organizations, with implemented quality control systems, should calibrate and test their measuring instrument between calibrations, in accordance with the requirements of adequate quality control systems. Requirements related to calibration and tests and also determining the periods of their frequency are defined in specific standards on production and research and other international documentation which serve as guidelines for various lines of trade. It is should be noted that, conformity assessment, WE verification and subsequent verification cannot substitute calibration.

Requirements of the selected standards within quality management systems in the scope of calibration and testing of measuring equipment: