Guides · Calibration
Calibration certificates: what to check
Last reviewed 31 Oct 2026
An auditor will look at your calibration certificates sooner or later. Here's what accreditation means and what to check on each certificate before you file it.
What SAC-SINGLAS accreditation means
The Singapore Accreditation Council (SAC) runs SAC-SINGLAS, the Singapore Laboratory Accreditation Scheme. Accredited calibration companies are assessed against ISO/IEC 17025, the international standard for the competence of testing and calibration laboratories. Certificates from SAC-SINGLAS accredited companies are recognised in other economies through international mutual recognition arrangements. (SAC)
Accreditation covers a scope, not the whole company
SAC grants accreditation only for specific calibrations in specific fields, and a company may issue accredited certificates only for those. A company accredited for pressure gauges isn't automatically accredited for oscilloscopes. Each company's scope lists the instrument types, ranges and measurement uncertainty it is accredited for. You can look up accredited companies in SAC's directory of accredited organisations.
What to check on the certificate
- The accreditation mark. It shows the calibration was done within the company's accredited scope.
- Your instrument. The make, model and serial number match the instrument in your hands.
- The date of calibration.
- Results with measurement uncertainty. Readings alone aren't enough. Each result should state its uncertainty.
- "As found" and "as left" readings, if the instrument was adjusted and you asked for both.
- Traceability. A statement that the measurements are traceable to national or international standards.
- Authorisation. The name or signature of the person who approved the certificate.
Who sets the next calibration date?
Usually you do. Under ISO/IEC 17025, a calibration company doesn't put a recommended recalibration interval on the certificate unless it has agreed that with the customer. Most teams base the interval on the maker's advice, how heavily the instrument is used, and its past results. If you want a due date on the certificate or label, ask for it when you book.
"Accredited" versus "traceable"
Some providers offer "traceable" calibration that isn't accredited. It can be cheaper and may be enough for some uses, but it hasn't been independently assessed. If your quality system or customer asks for accredited calibration, check for the accreditation mark.