Checking an instrument against standards of known uncertainty and recording how its readings line up with them, so later results can be corrected or qualified. Calibration by itself does not include adjustment: a meter can be calibrated, found in tolerance and returned untouched. Its output is the certificate data and uncertainty that make the instrument's readings traceable.
Calibration showed it 0.3 percent high at full scale, still in tolerance, so we recorded it and put a sticker on.
When a production manager says 'calibrate it', he usually means 'adjust it'; ask before you start turning pots.
Also heard as
- cal
Do not mix it up with
- Adjustment: Adjustment physically or electronically changes the instrument; calibration only measures and records how it performs.
Related terms
Adjustment
Changing an instrument so its readings move closer to the correct values, a step separate from calibration.
Verification
A check that an item is good enough for its stated requirements, usually ending in pass or fail with no full calibration data.
Traceability
Proof that a result ties back to the SI or another stated reference, with every calibration in between on record.
Calibration certificate
The document reporting a calibration's results, uncertainties, conditions and traceability for one specific item.
Calibration interval
The scheduled time between calibrations of an instrument, set to keep the chance of drifting out of tolerance low.