The measurement readings recorded after calibration adjustments have been completed, documenting the instrument's condition as it is returned to service.
As-left data documents the state of an instrument after all calibration adjustments, cleaning, and corrections have been performed. It confirms that the instrument meets its accuracy specifications and is fit for return to service. If no adjustment was needed (as-found data was within tolerance), the as-left data may be identical to the as-found data, or a fresh set of readings may be taken to confirm.
The as-left data serves as the starting-point reference for the next calibration cycle. It establishes the instrument's known good condition at the beginning of the new calibration interval. When the instrument returns for its next calibration, the new as-found data will be compared against the previous as-left data to assess how much the instrument has changed (drifted) during the interval.
For calibration management, both as-found and as-left data must be recorded and retained on every calibration record. The pair of datasets tells the complete story: as-found shows how the instrument performed in service, and as-left shows its condition as returned. This dual-record approach is required by ISO 17025, ISO 9001, and most quality standards. It enables trend analysis, interval optimization, and provides the documentation needed for audits and regulatory inspections. Calibration software should facilitate recording both datasets and flagging any as-left readings that remain outside tolerance.
In aerospace calibration labs, as-left data for a Fluke 8508A reference multimeter documents final accuracy readings after drift corrections, showing the instrument now measures within ±0.0015% for DC voltage ranges before returning to production test stations. Medical device manufacturers rely on as-left data when calibrating infusion pump flow meters - after adjusting the 10mL/hr setpoint that was reading 10.3mL/hr, the as-left reading of 10.02mL/hr confirms specification compliance before patient-critical use. Defense contractors must capture as-left torque wrench readings after recalibration; if a 50 ft-lbf wrench showed 52.1 ft-lbf as-found but only 49.8 ft-lbf as-left after adjustment, this indicates incomplete correction requiring further investigation. Common audit findings occur when labs record as-left data identical to as-found readings without performing actual adjustments, or when as-left values still exceed specifications but instruments are returned to service anyway. Missing as-left documentation creates traceability gaps that auditors flag as non-conformances, particularly when measurement uncertainties cannot be verified against the instrument's actual departure condition.
ISO/IEC 17025:2017 Section 7.8.4.1 requires laboratories to maintain records of calibration results including 'after adjustment' measurements, which encompasses as-left data. AS9100D Section 7.1.5.2 mandates documented evidence of measurement equipment condition after calibration activities. ISO 13485:2016 Section 7.6 requires records showing measuring equipment meets requirements before release, making as-left verification critical. ANSI/NCSL Z540.3-2006 Section 10.3.2 specifically addresses post-adjustment verification requirements. IATF 16949:2016 Section 7.1.5.1.1 requires statistical studies when gauge capability is inadequate, often triggered by as-left performance data. Auditors examine as-left records to verify instruments actually meet specifications after calibration, looking for evidence that adjustments were effective and measurement uncertainty calculations reflect actual instrument performance rather than specification limits. They also verify as-left data supports conformity statements on calibration certificates and that out-of-specification as-left readings trigger appropriate investigation and corrective actions.
CalibrationOS captures as-left data through its Calibration Execution module, automatically recording final measurement readings after each adjustment step in the calibration procedure. The system enforces as-left data entry before allowing calibration completion, preventing incomplete records. During multi-point calibrations, the software compares as-left readings against acceptance criteria and measurement uncertainty budgets, flagging instruments that remain out-of-specification. The Certificate Generator module includes as-left values in conformity statements, while the Audit Trail feature maintains immutable timestamps showing when as-left measurements were recorded. The Quality Dashboard provides statistical analysis of as-left versus as-found data trends, helping labs identify systematic calibration issues. During audits, the software generates compliance reports showing complete as-left documentation for any specified time period, with direct links to supporting measurement data and uncertainty calculations that demonstrate traceability to national standards.
As-left data is the set of measurement readings recorded after calibration adjustments are completed. It confirms the instrument meets specifications and documents its condition as returned to service.
Yes. Quality standards require both. As-found data shows the instrument's condition during use, and as-left data confirms it meets specifications after any adjustments. If no adjustment was made, the as-left data may equal the as-found data.
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