As-Found / As-Left Calibration Documentation
The record that tells you what your scale was actually doing — before and after calibration.
What As-Found and As-Left Documentation Actually Records
Every calibration visit produces two snapshots. The as-found record captures how the scale was performing before the technician made any adjustment — the instrument's real-world condition at the moment of arrival. The as-left record captures performance after calibration is complete — the verified condition when the technician departed.
Most calibration certificates show only as-left data. That's the "passed" snapshot most people think of. But as-found data is where the critical information lives — it tells you what the scale was doing during active use since the last calibration, not what it did after adjustment. The difference between those two things is the difference between documentation that supports compliance and documentation that creates risk.
Why As-Found Data Matters: Three Critical Applications
1. Out-of-Tolerance Investigation and Record Integrity
If a scale is found out of tolerance at calibration, that finding has immediate implications for every measurement made since the previous visit. In pharmaceutical manufacturing, this triggers an OOT investigation to assess batch record impact. In grain elevator or aggregate operations, it raises questions about commercial transactions settled on those weights. Without as-found data, there is no quantitative basis for bounding the extent of the potential inaccuracy. With it, you can answer the investigation with specificity — and may be able to conclude the impact was within acceptable limits without a full record review.
2. Calibration Interval Optimization
A single calibration tells you whether the instrument is in tolerance. A calibration history with as-found data at every visit tells you how fast the instrument drifts — the stability profile over time. That data is the basis for a defensible, science-based calibration interval. FDA 21 CFR Part 211, ISO 9001, and ISO/IEC 17025 all require calibration intervals be based on demonstrated instrument stability, not arbitrary fixed schedules. As-found history is the data that justifies your intervals to auditors.
3. Audit Defense and Quality System Evidence
When a quality auditor reviews your calibration program — FDA investigator, ISO 9001 registrar, customer quality rep, or MDARD inspector — they look for evidence of an effective measurement control program. A certificate showing only as-left performance is evidence the scale was adjusted on a particular date. A record with as-found data, as-left data, uncertainty information, traceability chain, and environmental conditions is evidence of a functioning measurement control system. Auditors know the difference.
What a Complete Calibration Record Should Include
Header and Instrument Identification
Asset number, make, model, serial number, location, capacity, readability, date and time of calibration, technician identification, and reference to the applicable calibration procedure.
Reference Standard Traceability
For each reference weight used: certificate number, issuing laboratory, calibration date, expiration date, nominal value, and certified value with uncertainty. The traceability chain to NIST must be unbroken and current. Expired reference weight certificates break the chain and invalidate the traceability claim for any calibration performed with those standards.
Environmental Conditions at Calibration
Temperature, humidity, and for precision laboratory balances, barometric pressure. For scales in environments where conditions affect performance, the record should note whether calibration conditions are representative of normal operating conditions.
As-Found Performance Data
At each test point — typically zero, 25%, 50%, 75%, and 100% of operating range — the nominal test weight, the indicated reading, and the error (indicated minus reference). For scales with multiple zones, corner loading results at each position. Recorded before any adjustment, zeroing, or span change.
As-Left Performance Data and Pass/Fail Determination
The same test points after all adjustments, with an explicit statement of the tolerance applied, whether the as-found condition was within or outside that tolerance, and whether the as-left condition meets the requirement. A certificate that omits an out-of-tolerance as-found finding is a data integrity failure — not a solution to one.
FAQs
Does every calibration need as-found data?
Yes — and in regulated environments, emphatically yes. There is no valid quality reason to perform a calibration adjustment without first recording what the instrument was doing. The only reason to omit it is to avoid documenting an out-of-tolerance condition, which creates more risk than it avoids. Cech documents as-found performance on every calibration visit, as standard practice.
How long should calibration records be retained?
Retention requirements vary by framework. FDA GMP regulations require measurement records through product traceability periods — typically at least one year beyond product expiration. ISO 9001 requires retention per the organization's document control procedure. At minimum: retain for the full instrument life plus one complete calibration cycle.
What if my calibration provider doesn't supply as-found data?
Request it. If they cannot or will not provide as-found documentation as a standard part of the certificate, that gap creates compliance risk for your quality management system. Cech provides complete as-found and as-left documentation on every calibration — not as an add-on, as the baseline.
Our Quality Guarantee
At Cech Scale, three generations of German precision and decades of field experience guide every install, calibration, and repair. When our name goes on the work, it carries that lineage, sets the standard we live by, and stands as a promise to perform today and for years to come.
