Out-of-Tolerance Calibration Results: How to Assess Their Impact and Decide What to Do Next

An out-of-tolerance calibration result shows that measuring equipment did not meet a defined requirement at the time of calibration. This finding does not automatically prove that every earlier measurement was wrong. It does, however, require a structured review. The organisation should confirm the result, understand the size and direction of the error, identify the period that may be affected, and evaluate the importance of previous measurements. This working paper presents a practical method for handling such cases. It separates equipment correction from impact assessment, explains the value of as-found data, and discusses risk-based decisions, records, customer communication, and medical metrology examples. The main conclusion is that a failed calibration result is not only an equipment problem. It is also a question about the validity of work performed before the failure was discovered.