Just like the people who use them, gauges should have periodic physical examinations. Sometimes, gauge calibration is needed to identify the seriousness of a known problem, and sometimes it uncovers problems you didn’t know existed.

But as with a human exam, the main reason for the annual checkup is to prevent problems from occurring in the first place.

The accuracy of a gauge can only be known by reference to a higher standard. Thus, gauges are set to masters that are more accurate than the gauge. These masters are certified against gauge blocks produced to a higher standard of accuracy, ultimately traceable to nationally or internationally recognized “absolute” standards that define the size of the dimensional unit. This is the line of traceability which must be followed for calibration to be valid.

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