Calibration check

Choose the decision rule deliberately

A simple rule compares the error with the tolerance. A guarded rule also considers the entered expanded uncertainty when evaluating acceptance. Those rules can give different outcomes near a limit. Agree on the rule appropriate to the work instead of switching it to obtain a passing result.

A worksheet is not a calibration certificate

This tool records the values and checks you enter. It does not establish reference traceability, environmental control, a complete uncertainty budget, or compliance with a calibration procedure. Retain the supporting records and identify the instrument, reference, and conditions separately when they are required.

Interpreting error and acceptance separately

If an instrument indicates 10.02 mm against a 10.00 mm reference, its indication error is positive 0.02 mm. A correction applied to compensate for that error would have the opposite sign. This worksheet reports the comparison; it does not automatically rewrite the instrument's calibration or apply corrections to future measurements.

Tolerance defines the acceptance boundary, while measurement uncertainty describes doubt about the measured error. They are not two names for the same quantity. Near a boundary, a guarded decision rule can give a different classification from a simple error-only rule because it includes the entered uncertainty. Record the chosen rule before reviewing results. Use reference values and units that correspond to each point, and check repeated points separately if they describe hysteresis or repeatability. A table of passing points does not prove performance between them or establish traceability. Retain the reference identification, environmental conditions, procedure, and uncertainty evidence needed for the actual calibration record.

Formula

Indication error = reading − reference. Guarded acceptance requires |error| + expanded uncertainty ≤ tolerance.