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    Calibration

    Also known as: Instrument calibration, Calibration of measuring equipment

    Definition

    An operation that relates a measuring instrument's indications to reference values of known uncertainty, so that later readings can be corrected or trusted.

    Editorial definition: The QHSE Standard, updated 3 October 2026 · https://qhsetech.com/glossary/calibration

    Scope: Calibration is not adjustment or verification, and traceability belongs to a result, not to an instrument or a laboratory. The user sets intervals; ISO 9001 and ISO 13485 text is not reproduced.

    Example for your evaluation: Follow one gauge found out of tolerance from its as-found reading to the lots it measured since its last good calibration.

    Sources checked: . Examples are editorial illustrations.

    What the VIM, NIST, FDA, ILAC and ISO's records say about calibration

    On this page calibration means what the International Vocabulary of Metrology, JCGM 200:2012, defines: an operation that, under stated conditions, relates the values of measurement standards and their uncertainties to an instrument's indications, then uses that relation to obtain a result from an indication. The outcome can be a statement, a function, a curve or a table, or simply a correction. The VIM's notes and annotations separate calibration from adjustment, often wrongly called self-calibration, which makes a measuring system give prescribed indications, and from verification, which confirms that stated requirements are met. Both come after calibration. This is general information, not legal or certification advice.

    NIST's policy adopts the VIM's definition of metrological traceability: a result can be related to a reference through a documented, unbroken chain of calibrations, each adding to the uncertainty. NIST's answers to frequent questions say that only results can be traceable, never an organisation or a laboratory, that the provider of a result supports the claim and the user judges it, and that using an instrument calibrated at NIST is not enough by itself. For a valid claim NIST lists the property measured, a full description of the measuring system, a result with an evaluated uncertainty, the reference as it stood when the system was compared with it, and internal measurement assurance programmes for both. Traceability alone does not show fitness for purpose, because the uncertainty must also be small enough.

    For medical devices, FDA's Quality Management System Regulation took effect on 2 February 2026 and incorporates ISO 13485:2016 by reference. The current text of 21 CFR part 820, shown by the eCFR as up to date on 20 October 2026, has no calibration section: section 820.10 requires a documented system meeting the applicable ISO 13485 requirements, and subparts C to O are reserved. Before then, section 820.72 required routine calibration, checking and maintenance of measuring and test equipment, limits for accuracy and precision, and, when limits were not met, remedial action and an evaluation of any adverse effect on device quality. It asked for standards traceable to national or international standards where practical, and for records of the equipment identity, calibration dates, who calibrated and the next due date.

    ILAC's guidance list includes G24:2022, which helps laboratories and other bodies that rely on measuring equipment to set and review recalibration intervals for the equipment they control. ISO's records show ISO 10012:2026, on requirements for measurement management systems, published in February 2026 as a second edition that replaces the 2003 edition and follows the harmonised structure of management system standards, and ISO 9001:2026, published in September 2026. These ISO standards and ISO 13485 are paid and were not read for this page.

    What we could not verify on 22 October 2026: the clause numbers and titles that cover measuring equipment in ISO 9001:2026 and ISO 13485:2016, commonly cited for the withdrawn 2015 edition of ISO 9001 as 7.1.5, monitoring and measuring resources, and for ISO 13485 as 7.6, control of monitoring and measuring equipment, and whether the 2026 edition keeps that numbering; any public primary text defining the terms as-found and as-left, used on this page for readings taken before and after adjustment; and how accreditation bodies now apply ILAC's G24.

    Sources opened :

    What a calibration record holds in software

    • The instrument's unique identity, type, range, location and owner, and the measurements it is used for.
    • The tolerance required for each use, which a calibration result is judged against.
    • Each calibration: date, who performed it, the procedure, the conditions and the reference standards used.
    • Readings before any adjustment and after it, each with its uncertainty and a pass or fail decision.
    • The certificate or report, with the provider's traceability statement and, where relied on, the accreditation scope.
    • The interval chosen, the reason for it, the next due date and every later change to the interval.
    • For a failed result, the products or tests measured since the last good calibration, the impact assessment and the decision.

    Calibration, adjustment, verification, traceability and measurement system analysis

    Calibration gives the relation between an instrument's indications and reference values, with its uncertainty. Adjustment changes the instrument so that it reads as prescribed. Verification is a pass or fail against a stated requirement, and it depends on a calibration. Metrological traceability belongs to a result, not to a laboratory or a label on the instrument. Measurement system analysis studies how measuring varies in use, with operators, parts and time.

    A hypothetical example: a micrometer found out of tolerance

    Everything in this case is invented and describes no real company. A turning subcontractor with 25 staff checks a shaft diameter of 25.000 mm, with limits of plus or minus 0.020 mm, using a micrometer whose tolerance for this use is plus or minus 0.004 mm. The interval is six months, and the last good calibration was on 10 March. On 9 September the laboratory records an as-found error of +0.009 mm, more than double the tolerance, and after adjustment an as-left error of +0.001 mm. Between the two dates the micrometer accepted 1,240 shafts in 31 lots.

    The quality lead opens an impact assessment and assumes the error may have existed since 10 March, because an as-found result cannot show when drift began. The micrometer read high, so a shaft accepted with a reading below 24.989 mm may truly be under the lower limit of 24.980 mm; shafts near the upper limit were not at risk. The records show 37 shafts read between 24.980 mm and 24.988 mm, in 6 lots, which is 37 of 1,240, or 3.0%. Four of those lots are still in stock and are re-measured; two have shipped, so their customers are told. The interval is cut to three months until two further calibrations pass, and the reasons are recorded.

    Common misunderstandings about calibration

    • A calibration label is not proof of traceability. NIST adds that one of its own test report numbers does not prove it either.
    • Calibration is not adjustment. The VIM keeps them apart, and an instrument can be calibrated without being adjusted at all.
    • Calibrated does not mean fit for purpose. NIST says the uncertainty must also be small enough for the measurement need.
    • The end of section 820.72 did not end the subject for device makers. Part 820 now requires a system that meets the incorporated ISO 13485 requirements, whose text on measuring equipment was not read.
    • An accredited laboratory does not vouch for every later reading. NIST calls accreditation a finding of competence for a scope, and its own results apply to the instrument at the time of test.

    How calibration relates to other glossary terms

    Calibration supplies the reference that many quality records depend on. These terms sit around it.

    • Measurement system analysis: the study of how the measuring process varies in use, beyond what a certificate shows.
    • Quality control: the checks whose accept and reject decisions rest on calibrated measurements.
    • Non-conformance: the record raised for product accepted with an instrument later found out of tolerance.
    • ISO 13485: the device standard that part 820 has incorporated by reference since 2 February 2026.
    • CAPA: where the root cause of a failed calibration, such as an interval set too long, is removed.

    Records and evidence that usually exist for calibration

    • An equipment register with identity, location, range, tolerance and due date for every instrument in scope.
    • Calibration certificates or reports with results, uncertainty and a traceability statement.
    • Records of the reference standards and of the laboratories used, with the accreditation scope where it is relied on.
    • Out-of-tolerance reports with the impact assessment, the lots affected and the decision.
    • Interval reviews, with the calibration history behind each change.

    What a software tool needs to capture for calibration

    • One record per instrument, with the tolerance for each use rather than only the maker's specification.
    • Due dates driven by an interval the organisation sets and can change, with the reason kept.
    • Separate fields for readings before and after adjustment, so a failed result is never overwritten by a passed one.
    • A hold on overdue or failed instruments, with who released them and why.
    • A link from each instrument to the inspections, lots or tests it was used for, so an impact assessment can find them.
    • A change history that cannot be silently edited, and an export for auditors and inspectors.

    Catalog profiles documenting calibration records

    Profiles appear here under the calibration management software guide's rule, which needs a matching tag and a sourced calibration or gauge capability. The rule does not show that a product keeps readings from before and after adjustment or links an instrument to the lots it measured, so test both with your own equipment list.

    Same rule for every product: tagged “Calibration Management”, “Quality Management”, “Asset Management”, “Equipment Maintenance” or “Equipment Inspection”, with a sourced calibration capability in its record, or one the vendor stated to us, labelled as vendor-stated. Documented and conditional capabilities qualify; check the linked scope before treating a module as included.

    Ordered by how closely our sources document this process, not by quality. Sponsored placements are labelled. How lists are ordered

    All 9 matching profiles are shown. Documentation review, not hands-on testing or a claim of compliance.

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    Frequently asked questions

    How often should equipment be calibrated?

    No source read for this page fixes one interval for all equipment. ILAC's G24:2022 is guidance on how to set and review recalibration intervals, and NIST asks for traceability to be checked again from time to time, judged on the measurement need, the dependability of the equipment and the environment. Record the interval, its reason and every change.

    What is the difference between calibration and verification?

    Calibration finds how an instrument's readings relate to reference values and with what uncertainty. Verification uses that information to decide whether a stated requirement, such as a maximum permissible error, is met, and the VIM's annotation calls calibration a prerequisite for it. One gives a relation, the other a pass or fail.

    What should happen when an instrument is found out of tolerance?

    Until 1 February 2026, 21 CFR 820.72 asked device makers to take remedial action and to document whether device quality had suffered. The current part 820 relies on ISO 13485, which was not read. A sound record lists what was measured since the last good calibration, judges each result against its tolerance and keeps the decision.

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