Do you need a calibration certificate if you already have a declaration of conformance?
Applies to: ISO 6789-1:2017, ISO 6789-2:2017 · Updated 2026-10-27
Technical review: Alston Hsiao (Chieh-Jen Hsiao), CTO, STAND
It depends on the intended use: if you need traceable calibration results and measurement uncertainty for this individual tool, you need a Part 2 calibration certificate. A declaration of conformance addresses whether the tool meets Part 1 requirements. A calibration certificate reports how that tool measured during calibration. Decide what you need to establish before deciding whether to obtain both.
Define the evidence you need
A declaration of conformance may include a serial number, measurement values, and uncertainty information. The key is what that information concerns. A Part 1 declaration reports the measurement device's error and uncertainty interval; a Part 2 certificate reports W and W′ for the tool being calibrated at each calibration point. If your work requires the latter, the former alone is insufficient.
| What do you need to establish? | Which document should you check? |
|---|---|
| Whether observed values for the delivered tool are within the Part 1 permissible deviation | The decision in the declaration of conformance |
| How this tool measured at each calibration point, with uncertainty and traceability information | A calibration certificate issued to Part 2 |
| Both conformance at delivery and individual calibration results | Check each kind of evidence; you can agree to receive both a declaration and a certificate |
For example, purchasing may need to confirm conformance on receipt, while quality control needs uncertainty at each calibration point to assess suitability for measurement work. Each document then serves a purpose. This example does not mean that every customer or every task requires both.
Can a calibration certificate replace all conformance evidence?
Measurement results from one tool's calibration cannot, on their own, establish whether its model has completed design conformance testing or demonstrate every aspect of quality conformance. Conformance at the design and manufacturing stages still needs to be checked against Part 1 testing and the associated evidence.
This does not mean that every new tool must come with two documents. Part 1, Clause 5.2, allows a conforming tool to be supplied with a declaration of conformance or a calibration certificate issued to Part 2. That document-delivery option does not expand a single calibration to cover all design and quality tests.
How should you specify the requirement when purchasing?
State the standard's part and year, then explain whether you need a conformance decision, individual calibration results, or both. If you have already received a declaration and later discover that a calibration certificate is needed, first check whether a Part 2 certificate already exists for the tool. If it does not, arrange the required calibration.
On receipt, cross-check the tool type, serial number, and document reference. Whether the evidence is sufficient depends on its actual contents and your requirements. Neither the document's title nor the number of documents supplied is enough to make that decision.