ISO/IEC 17025 is the international standard that defines the competence of testing and calibration laboratories. When a lab is accredited to ISO/IEC 17025 — in Singapore, by SAC-SINGLAS — an independent national body has assessed and confirmed that the lab is technically competent, uses validated methods, maintains metrological traceability to national standards, and reports measurement uncertainty correctly. An accredited calibration certificate is therefore objective, third-party-verified evidence that your instrument reads true.

ISO/IEC 17025 vs a "traceable" or "in-house" calibration

Many suppliers issue a calibration certificate that is traceable but not accredited. The difference matters:

  • Accredited (ISO/IEC 17025): The lab's competence, methods, environment, staff and uncertainty budgets have been audited by an accreditation body. The certificate carries the accreditation mark and a schedule of accreditation.
  • Traceable only: The reference standards may trace back to a national institute, but no third party has verified the lab's actual measurement process or uncertainty.
  • In-house / manufacturer: Useful for routine checks, but typically not accepted as independent evidence in a regulated audit.

For quality systems (ISO 9001), GMP, aerospace, or any regulated environment, auditors generally expect ISO/IEC 17025-accredited calibration for measurements that affect product quality or safety.

What an accredited certificate must contain

A compliant ISO/IEC 17025 calibration certificate states the measured values, the reference standards used, the environmental conditions, the metrological traceability chain, and — critically — the measurement uncertainty for each point. It does not simply say "pass". It gives you the numbers so you can judge fitness for your own tolerance.

Why measurement uncertainty is the heart of it

Every measurement has uncertainty. ISO/IEC 17025 requires the lab to calculate and report it, so you can apply a proper guard band when deciding whether your instrument is still fit for purpose. A certificate without uncertainty is incomplete — you cannot make a defensible pass/fail decision from it.

Accreditation in Singapore: SAC-SINGLAS

In Singapore, laboratories are accredited under the Singapore Accreditation Council (SAC) SINGLAS scheme. SAC is a signatory to the ILAC Mutual Recognition Arrangement, which means a SAC-SINGLAS calibration certificate is recognised internationally — important for exporters and multinational quality systems.

When you need ISO/IEC 17025 calibration

  • Instruments used to release product, or to make safety or compliance decisions
  • Measurements cited in an ISO 9001, GMP, HACCP or regulatory audit
  • Reference instruments used to check or calibrate other equipment
  • Any situation where a customer, regulator or auditor asks for "accredited" calibration

Unitest Instruments operates a SAC-SINGLAS accredited calibration laboratory (ISO/IEC 17025). If you are unsure whether your application needs accredited calibration, send us the instrument list and the standard you are being audited against and we will advise.