• accredited calibrations should only be reserved for reference measurement standards,
• accredited calibrations are not needed if the required measuring instrument accuracies are low (broad tolerance limits),
• accredited calibrations are very expensive,
• calibrations by ISO 9000 certified laboratories guarantee traceability.

All calibration laboratories need accredited or provable internationally traceable calibration for their entire measuring equipment. Accredited calibration is also required for all testing laboratories, so as to be able to determine the compliance of products with standard or customer requirements.

All organisations, institutions or companies which, on the basis of measurements, issue opinions on compliance with requirements and/or limit values, need accredited calibration. It is required for all companies that assure the quality of their products or services on the basis of measurements. It is also needed when and where payments, orders, or collection are based on measurements, or where measurements assure safety, correct diagnosis, etc.

In practice, this means that accredited calibration is required by everyone who wants to have a proven traceability of their measuring instrument to an international level.

Accredited calibration is not necessary only where measurement traceability cannot be directly assured or is irrelevant. In these cases, it is possible to assure the validity of measurement results by participating in interlaboratory comparisons, by use of certified reference materials, with additional testing according to an alternative method, or by use of the agreed measurement standards recognised by all parties involved.