Accredited calibration and calibration with an ISO report: differences and selection criteria
Requirements for the precision and reliability of process data call for compliance with quality management standards. Every standard, from ISO 9001 to GMP, requires regular calibration of the instruments used for work, inspection, measurement and testing, in order to obtain accurate, reliable and traceable results.
Managing measuring equipment is therefore a requirement common to internationally recognized management systems: it concerns every organization that uses measuring or weighing instruments in its process. The result of calibration is documented with an accredited calibration certificate or with a calibration report.
This page explains the differences between the two calibration services, accredited calibration and calibration with an ISO report, and the criteria for choosing which one to request for each instrument, based on the requirements of your own management system and of your customers.
Questions this page answers
- What is the difference between accredited calibration and calibration with an ISO report?
- Which service should be requested for each instrument?
- When should you move from an ISO calibration report to a LAT certificate?
- What applies in the different sectors?
- How do the two services compare, point by point?
- How is traceability demonstrated in an audit?
ISO calibration report and LAT calibration certificate: what are the differences?
Accredited calibration
Performed by a laboratory accredited to UNI CEI EN ISO/IEC 17025 by an accreditation body (in Italy, ACCREDIA), for the quantities, instruments and measurement ranges within its scope of accreditation.
- Oversight
- Assessment and periodic surveillance by the accreditation body
- Result
- Accredited calibration certificate, with the accreditation body's mark and the laboratory number
- In an audit
- Traceability supported by the accreditation; scope and validity on the laboratory's public record
Calibration with an ISO report
Performed by a laboratory or a technical service without accreditation for that calibration, within the provider's management system, normally ISO 9001 certified.
- Oversight
- Procedures of the provider's management system
- Result
- Calibration report, without an accreditation mark
- In an audit
- Traceability documented by the provider's evidence, assessed by the user
The requirements are set by whoever uses the instrument
In short, for both the LAT calibration certificate and the non-accredited calibration report, the user must define, within their own management system, the metrological requirements of the instrument according to its intended use, considering factors such as frequency of use, production volumes, criticality of the measurements and instrument drift. The measuring range, the calibration points, the required uncertainty and the acceptance criteria for the results must be defined.
Both services give traceable results
Both types of service can provide metrologically traceable results, provided that the applicable requirements are met and traceability is adequately demonstrated. A non-accredited laboratory can also have and document the necessary technical competence; it is however up to the user to assess its adequacy on the basis of the available evidence.
The laboratory’s competence has been assessed by ACCREDIA
The LAT calibration certificate provides independent attestation of the laboratory’s competence, assessed by ACCREDIA for the activities within the scope of accreditation. In this respect, it is qualified evidence of accredited competence and of the metrological traceability of the results, without replacing the user’s assessment of whether the instrument is fit for its intended use.
The provider’s competence is assessed by the user
The non-accredited calibration report can document technically valid and metrologically traceable results, but the competence of the provider and the adequacy of the evidence must be assessed by the user. Even complete documentation does not give the report the international recognition that comes from accreditation.
Recognised abroad too
The LAT calibration certificate benefits from the recognition provided by the applicable international mutual recognition arrangements, provided that the specific activity falls within the laboratory’s scope of accreditation. This supports the recognition and acceptance of the results where formally recognised metrological evidence is required.
Accepted case by case by whoever receives it
The non-accredited calibration report may be accepted by the recipient on the basis of the applicable requirements and the available evidence, but it does not benefit from the same recognition as accreditation.
If a requirement calls for accredited calibration, it must be met
When standards, legal provisions, specifications or contractual requirements call for accredited calibration, that requirement must be met. In other cases, the choice between the two services must follow from the analysis of the requirements, the intended use of the instrument and the risk assessment.
The user always confirms that the instrument is fit for use
In both cases, the user must check that the calibration results and the associated uncertainty are suitable for the intended use and confirm the metrological fitness of the instrument.
Decision path
Four questions for each instrument. The path stops at the first yes.
Precondition. Accredited calibration is possible only if the quantity, instrument and measurement range fall within the laboratory's scope of accreditation. Otherwise, another accredited laboratory is used or, if the requirements allow it, calibration with an ISO report.
The choice must follow from the analysis of the applicable standards and requirements and from the risk assessment. It is made for each instrument, considering its intended use, the criticality of the measurement and the needs of the process.
When should you move from an ISO calibration report to a LAT certificate?
The ISO calibration report can be suited to the needs of your process. The LAT calibration certificate, issued under ACCREDIA accreditation, is the right choice when accredited calibration and specific requirements for technical competence and metrological traceability are needed.
When should the move to the LAT certificate be assessed?
- When it is expressly required by standards, specifications, internal procedures or customer specifications.
- When the company quality system provides for the use of accredited calibrations.
- When the calibration must be documented within processes or checks that require specific evidence of accreditation.
Before choosing, check the requirements that apply to your instruments and their use. This will help you identify the calibration service best suited to your actual needs.
The technical distinction matters: LAT accreditation attests the laboratory’s competence for the activities within its scope of accreditation and supports metrological traceability. It is not correct, however, to state in general that an ISO report does not ensure traceability or is not «accepted»: the assessment depends on the service performed and on the applicable requirements.
Service adequate
Calibration with an ISO report
- The applicable requirements do not expressly call for accredited calibration.
- Metrological traceability is ensured and documented in a way suited to the use of the instrument.
- The metrological performance and the measurement uncertainty are suited to the needs of the process.
Accreditation requirement or need
Calibration with a LAT certificate
- A customer, a specification, an applicable standard or a procedure requires accredited calibration.
- The micro-dispenser or balance is used for measurements critical to product quality, process conformity or reliability of results, and a formal guarantee of competence under accreditation is considered necessary.
- The micro-dispenser or balance is used to check other instruments or for measurements that require specific accredited metrological evidence.
- An ACCREDIA accredited calibration certificate is wanted, after checking that the specific activity falls within the laboratory’s scope of accreditation.
Two services in the same system
Both types of calibration can coexist in the same management system. The choice must follow from the analysis of the applicable standards and requirements and from the risk assessment. It is made for each instrument, considering its intended use, the criticality of the measurement and the needs of the process.
- LAT accredited calibrationinstruments for which the applicable requirements or the risk assessment make accredited calibration necessary or advisable
- Calibration with an ISO reportall other instruments for which the service is suited to the requirements and the intended use
The type of calibration and the calibration interval must be suited to the actual use of the instrument.
On receipt of the calibration report or the LAT certificate, the user must always check that the documentation and the results meet the defined criteria, including, where applicable, the identification of the instrument, the measurement uncertainty, the results obtained and the statements of conformity.
The outcome of the check — acceptance or non-acceptance — and the related evidence must be recorded in the management system and kept in the metrological file of the instrument, to support the confirmation of its metrological fitness for the intended use in the metrological confirmation process.
Examples by sector
The following indications are for guidance only. The choice between a non-accredited calibration report and a LAT calibration certificate must be based on the applicable regulatory and contractual requirements, the procedures of the management system, the use of the instrument and the risk assessment.
ISO/IEC 17025 testing laboratory
- Reference
- UNI CEI EN ISO/IEC 17025, clause 6.5, requires the laboratory to ensure the metrological traceability of its measurement results. The ILAC P10 policy defines the criteria for demonstrating such traceability.
- Guidance
- Accredited calibration should be preferred when available for the specific quantity, measuring range and required metrological performance. The use of non-accredited calibrations must be supported by documented evidence showing that the applicable requirements are met.
Pharmaceutical quality control
- Reference
- The choice of calibration must comply with the applicable GMP requirements, the company procedures and the specific needs of the process. Chapter 2.1.7 of the European Pharmacopoeia covers balances for analytical purposes.
- Guidance
- The choice between a non-accredited calibration report and a LAT certificate must consider the criticality of the measurements, the required uncertainty, the company procedures and any customer requirements. Accredited calibration is required when expressly called for by the applicable requirements and may be advisable for instruments that significantly affect the reliability of results.
Food sector and food testing laboratories
- Reference
- For testing laboratories accredited to UNI CEI EN ISO/IEC 17025, the requirements on metrological traceability and equipment management apply. Schemes such as ISO 22000, BRCGS and IFS must be assessed according to the applicable version and the specific requirements of the organisation.
- Guidance
- The choice of calibration must consider the laboratory’s activity, the use of pipettes and micro-dispensers, the criticality of the measurements and customer requirements. Accredited calibration is required when called for by the applicable requirements; in other cases, both types of service can be assessed according to the metrological needs and the risk assessment.
Production with an ISO 9001 system
- Reference
- UNI EN ISO 9001:2015, clause 7.1.5.2, requires metrological traceability to be ensured when it is a requirement or when it is considered essential to ensure the validity of measurement results. The standard does not generally require the use of an accredited laboratory.
- Guidance
- Calibration with a non-accredited report can be adequate when it meets the metrological and documentary requirements defined by the organisation. LAT calibration must be chosen when required by an applicable requirement or when it is advisable given the criticality of the measurement, the use of the instrument and the needs of the quality system.
Comparison of the two services
Execution, method, location, options, result and value in an audit.
| Comparison | Accredited calibration | Calibration with an ISO report |
|---|---|---|
| Execution | Laboratory accredited by an accreditation body; in Italy, an ACCREDIA-accredited LAT calibration center | Laboratory or technical service, without accreditation for that calibration |
| Oversight | Accreditation to UNI CEI EN ISO/IEC 17025:2018, with periodic surveillance by the accreditation body | Provider's management system, normally ISO 9001 certified; no assessment by an accreditation body |
| Scope | Only quantities, instruments and measurement ranges within the scope of accreditation | Defined by the provider |
| Method and tests | Method included in the accreditation: for balances, the EURAMET cg-18 guide, with repeatability, eccentricity and linearity tests; for micro-dispensers, ISO 8655-6, with the gravimetric method | Method chosen by the provider, often the same guide or standard; for balances, repeatability, eccentricity and linearity tests |
| Location | As provided for in the scope of accreditation: at the customer's site or in the laboratory, depending on the quantity and the instrument | At the customer's site or in the laboratory |
| Options | Minimum weight according to the EURAMET cg-18 guide; statement of conformity with a decision rule according to the ILAC-G8 guide | As found and as left reports; Ph. Eur. 2.1.7 repeatability tests for the minimum weight and sensitivity test |
| Uncertainty | Expanded uncertainty, confidence level of approximately 95 %, not lower than the best uncertainty in the accredited scope | Expanded uncertainty, when stated, according to ISO/IEC Guide 98-3 (GUM) and document EA-4/02 |
| Traceability | Supported by the accreditation; recognition under the EA MLA and ILAC MRA arrangements | Documented with the certificates of the standards used and the provider's procedures |
| Conformity | Statement of conformity to a specification, as an option | Conformity assessment according to the stated limits, for balances for example EN 45501 or the customer's limits |
| Result | Accredited calibration certificate, with the accreditation body's mark and the laboratory number | Calibration report, without an accreditation mark |
| Value in an audit | Traceability supported by the accreditation; scope and validity on the laboratory's public record, on the accreditation body's website | Traceability evidence assessed by the user |
Traceability in an audit
With accredited calibration, traceability is supported by the accreditation: the certificate bears the accreditation body's mark and the laboratory number, and the scope of accreditation can be checked on the laboratory's public record.
With calibration with an ISO report, traceability is documented with the certificates of the standards used, referenced in the report, and with the provider's procedures. Assessing this evidence is up to the user.
At Gibertini
Accredited calibration, LAT center No. 00121
Analytical balances, precision balances, bench scales, platform scales, floor platforms, industrial scales and load cells, at the customer's site. Pipettes, syringes, dispensers, diluters and burettes, in the Novate Milanese laboratory.
View the accredited scope and uncertaintiesCalibration with an ISO report
Balances of any brand, platforms and silos; ovens, thermostats, incubators, capacity measures and other instruments on request. At the customer's site or in the laboratory.
View ISO calibration reportsDetails of the two Gibertini services
| Comparison | Accredited calibration (certificate) | Calibration with an ISO report |
|---|---|---|
| Issuer | LAT Calibration Center No. 00121, ACCREDIA-accredited | Gibertini technical service department |
| Third-party assessment | ACCREDIA accreditation to UNI CEI EN ISO/IEC 17025:2018, within the scope of the attached schedule | No assessment by an accreditation body; report issued within the ISO 9001 and ISO 14001 certified management system |
| ACCREDIA mark | Present, with the number LAT No. 00121 | Absent |
| Method for balances | EURAMET cg-18 guide, version 4.0 | Repeatability, eccentricity and linearity, according to the EURAMET cg-18 guide |
| Uncertainty | Expanded uncertainty, confidence level of approximately 95 %, not lower than the best uncertainty in the ACCREDIA schedule | Expanded uncertainty U with k = 2, confidence level of approximately 95 %, according to ISO/IEC Guide 98-3 (GUM) and document EA-4/02 |
| Traceability | Supported by the accreditation; recognition under the EA MLA and ILAC MRA arrangements | Working standards calibrated by ACCREDIA-accredited centers, with the references of the certificates of the masses used |
| Conformity | Balances: statement of conformity on request, with a decision rule according to the ILAC-G8 guide. Micro-dispensers: conformity to the maximum permissible errors of the applicable part of ISO 8655 | Conformity assessment always included: maximum permissible error according to EN 45501 or the customer's limits |
| Instruments | Balances (NAWI): analytical, precision, bench scales, platform scales, floor platforms and industrial scales; load cells. Micro-dispensers: pipettes, syringes, dispensers, diluters and burettes | Balances (NAWI) of any brand, platforms and silos; ovens, thermostats, incubators, capacity measures; other instruments on request |
| Location | Balances at the customer's site; micro-dispensers in the Novate Milanese laboratory | At the customer's site or in the laboratory |
| Options | Minimum weight according to EURAMET cg-18; Ph. Eur. 2.1.7, GMP and GLP checks, not accredited | Gold level on request: Ph. Eur. 2.1.7 repeatability tests for the minimum weight and sensitivity test, as found and as left reports |
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Accredited calibration certificate and ISO calibration report, on instruments of any brand.
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