Intermediate Checks Between Calibrations: How to Maintain Confidence Without Recalibrating Every Time

Calibration confirms the performance of measuring equipment at a stated time, but equipment can change before its next calibration. Intermediate checks help users detect significant changes during this period. They do not replace calibration and do not normally establish a new traceability chain. Their purpose is to maintain confidence that equipment remains suitable for use. This working paper explains how intermediate checks should be selected, performed, evaluated, and documented. It discusses check standards, control limits, trends, failed checks, and the relationship with calibration intervals. Examples from medical metrology show how simple checks can reveal drift, damage, leakage, connection problems, or unstable performance. The main conclusion is that an intermediate check is useful only when it is planned, sensitive to relevant faults, compared with predefined limits, and followed by appropriate action.