A calibration certificate is a proof that certifies the metrological properties of a calibrated measuring instrument. It is a document that defines the relationship between the standard and the instrument indications, with the specified uncertainty of measurement.  When calibrating measuring instruments, the measurement uncertainty should be estimated in accordance with document EA-4/02 ("Determination of measurement uncertainty during calibration"). It is a guide that standardizes the requirements for expressing the measurement uncertainty across Europe.

The calibration certificate with accreditation has the accreditation symbol "Calibration" with the accreditation number marked as "AP XXX". It is therefore a confirmation that the calibration of the measuring instrument was performed in an accredited laboratory having the competences confirmed by the Polish Centre for Accreditation (PCA).

The accredited calibration certificate gives the customer the certainty that the calibration was performed based on the CMC (calibration and measurement capability). Accreditation is a formal confirmation by a third party that a calibration body is competent to perform specific compliance assurance tasks. The only institution in Poland authorized to grant accreditation to laboratories is the Polish Centre for Accreditation (PCA).

The accredited calibration certificate contains PCA marks that increase its status, confirm the reliability of the results and are recognized all over the world.

Valid calibration certificate

• is a document, which is increasingly required for orders and acceptance of work related to the performance of measurements,
• is a form of security against the client's claims (e.g. in case of a failure),
• allows users to determine the metrological properties of the calibrated measuring instrument,
• contains designated corrections (errors) that can be taken into account in a given measurement procedure,
• allows users to analyse the results of cyclical calibrations that provide important data when determining the calibration intervals.