Calibration procedures, NIST-traceable standards, calibration intervals, and out-of-tolerance impact assessment — 820.72 calibration program structure preserved.
Measurement software and automated calibration tools must be validated; calibration status identification on equipment is explicitly required.
Software validation records for calibration tools and out-of-tolerance impact assessment documentation — unvalidated calibration software is a common 483 finding.
Maps to
QMSR / ISO 13485: §820.72 Inspection, measuring, and test equipment.
ISO 13485: §7.6 Control of monitoring and measuring equipment
Requirement text
Monitoring and measuring equipment needed to demonstrate conformity must be determined. Equipment must be calibrated at specified intervals, identified with calibration status, protected from damage, and calibration records maintained. Software used for monitoring and measurement must be validated before use.
Why this clause exists
Measurement equipment that has drifted out of tolerance makes every measurement made with it suspect — and unlike a failed production step that produces an observable defect, an out-of-tolerance measuring instrument produces results that appear valid while systematically misrepresenting the conformance of the product being measured. Calibration at defined intervals against reference standards traceable to national measurement standards is the mechanism that maintains confidence that measurements reflect reality rather than instrument drift. The out-of-tolerance investigation requirement exists because discovering that a measurement instrument was out of tolerance does not tell the organization which specific measurements were affected or when the drift began. Without a formal investigation that evaluates the impact on measurements made since the last valid calibration, a manufacturer cannot know whether product released during that period was actually conforming or was released on the basis of inaccurate data. Calibration status identification on each instrument prevents an operator from inadvertently using an instrument that is past its calibration due date — a control that requires no records review to implement at the moment of use. Measurement software validation applies the same principle as production software validation (REQ-ISO13485-7.5.6): software that executes measurement functions must be confirmed to perform those functions accurately before it is used to make conformance decisions.
What changed
§820.72 — Part 820 (legacy)
"Control of inspection, measuring, and test equipment. Each manufacturer shall ensure that all inspection, measuring, and test equipment, including mechanical, automated, or electronic inspection and test equipment, is suitable for its intended purposes and is capable of producing valid results. Each manufacturer shall establish and maintain procedures to ensure that equipment is routinely calibrated, inspected, checked, and maintained. The procedures shall include provisions for handling, preservation, and storage of equipment, so that its accuracy and fitness for use are maintained. These activities shall be documented. Calibration. Calibration procedures shall include specific directions and limits for accuracy and precision. When accuracy and precision limits are not met, there shall be provisions for remedial action to reestablish the limits and to evaluate whether there was any adverse effect on the device's quality. These activities shall be documented. (1) Calibration standards. Calibration standards used for inspection, measuring, and test equipment shall be traceable to national or international standards. If national or international standards are not practical or available, the manufacturer shall use an independent reproducible standard. If no applicable standard exists, the manufacturer shall establish and maintain an in-house standard. (2) Calibration records. The equipment identification, calibration dates, the individual performing each calibration, and the next calibration date shall be documented. These records shall be displayed on or near each piece of equipment or shall be readily available to the personnel using such equipment and to the individuals responsible for calibrating the equipment."
§7.6 — ISO 13485:2016 (current)
"The organization shall determine the monitoring and measurement to be undertaken and the monitoring and measuring equipment needed to provide evidence of conformity of product to determined requirements. The organization shall document procedures to ensure that monitoring and measurement can be carried out and are carried out in a manner that is consistent with the monitoring and measurement requirements. As necessary to ensure valid results, measuring equipment shall: a) be calibrated or verified, or both, at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards: when no such standards exist, the basis used for calibration or verification shall be recorded (see 4.2.5); b) be adjusted or re-adjusted as necessary: such adjustments or re-adjustments shall be recorded (see 4.2.5); c) have identification in order to determine its calibration status; d) be safeguarded from adjustments that would invalidate the measurement result; e) be protected from damage and deterioration during handling, maintenance and storage. The organization shall perform calibration or verification in accordance with documented procedures. In addition, the organization shall assess and record the validity of the previous measuring results when the equipment is found not to conform to requirements. The organization shall take appropriate action in regard to the equipment and any product affected. Records of the results of calibration and verification shall be maintained (see 4.2.5). The organization shall document procedures for the validation of the application of computer software used for the monitoring and measurement of requirements. Such software applications shall be validated prior to initial use and, as appropriate, after changes to such software or its application. The specific approach and activities associated with software validation and revalidation shall be proportionate to the risk associated with the use of the software, including the effect on the ability of the product to conform to specifications. Records of the results and conclusion of validation and necessary actions from the validation shall be maintained (see 4.2.4 and 4.2.5). NOTE Further information can be found in ISO 10012."
Δ Adds a requirement to assess validity of previous measurement results when out-of-calibration equipment is discovered, and mandates software validation for measurement applications — both absent from Part 820.
Common gaps (what we see in audits)
- Measurement Software Not Validated — Software used for monitoring and measurement (automated test systems, data acquisition software, Excel calculation spreadsheets, statistical analysis tools, database queries for quality trending) has not been validated. The calibration program covers physical instruments but excludes software tools from its scope.
- Out-of-Tolerance Impact Assessment Not Documented — When instruments are found out of tolerance during calibration, they are recalibrated or replaced, but there is no documented assessment of the impact on measurements taken since the last valid calibration. Products released based on potentially invalid measurements are not evaluated for conformity.
- Unvalidated calibration software — Software used to record calibration data or control an automated test fixture was never validated. ISO 13485 §7.6 requires software validation.
- Calibration Status Not Visible on Equipment — Calibrated equipment does not bear visible calibration status identification (calibration label with due date, color-coded status sticker, or equivalent). Users cannot readily determine whether an instrument is within its calibration period before use.
- Calibration Intervals Not Justified — Calibration intervals are set at arbitrary periods (typically annual) without technical justification based on instrument stability, measurement criticality, usage frequency, or manufacturer recommendations. Intervals have never been reviewed or adjusted based on calibration history data.