Lab slang for the internal self-calibration or autocal routine in high-end meters, calibrators and analyzers, which measures internal references and updates correction constants to cancel drift and temperature effects since the last full calibration. It improves short-term performance and is often a required step before a precision measurement. It does not replace external calibration, because the onboard reference itself still needs traceability.
Run a self-cal on the 8.5-digit meter first, the bench has moved three degrees since this morning.
Also heard as
- autocal
- self-calibration
- ACAL
- internal cal
Do not mix it up with
- Calibration: Self-cal only realigns the instrument to its own internal reference; external calibration ties that reference to traceable standards.
Related terms
Calibration
Comparing an instrument with a better-known standard and recording how its readings line up with the standard's values.
Adjustment
Changing an instrument so its readings move closer to the correct values, a step separate from calibration.
Drift
Gradual change in an instrument's readings over time that comes from the instrument itself, not from what it measures.
Traceability
Proof that a result ties back to the SI or another stated reference, with every calibration in between on record.