English version · Author: Khanh Nguyen · Content checked:
Quick answer
Calibration establishes the relationship between values indicated by a measuring instrument or measurement standard and reference quantity values. Legal metrological verification evaluates and confirms that a measuring instrument meets applicable metrological technical requirements. Inspection examines an item—such as a product, installation, process or service—and determines conformity with specified requirements.
All three activities may be needed in one factory, but they are not interchangeable. Identify the item, governing requirement and required deliverable before ordering a service in Vietnam.
The words calibration, verification, checking and inspection are sometimes used loosely in purchasing conversations. That can lead to an incorrect scope or a document that does not serve its intended purpose. This guide explains the distinctions using official sources. It is general information, not a determination of the legal requirements for a specific instrument or item of equipment.
Calibration, verification and inspection compared
| Activity | Main question | Typical subject | Deliverable to clarify |
|---|---|---|---|
| Calibration | How does the instrument indicate compared with reference values? | Measuring instrument or measurement standard | Measurement results, conditions and relevant uncertainty information within the service scope |
| Legal metrological verification | Does the measuring instrument meet applicable metrological technical requirements? | An instrument subject to, or requested for, verification | A conclusion and the applicable mark, stamp or certificate |
| Inspection | Does the item conform to specified requirements? | Product, installation, plant, process or service | Report or certificate under the agreed inspection scope and criteria |
The exact name and legal effect of a deliverable depend on the applicable regime. A buyer should therefore state the intended use instead of asking only for an “ISO certificate”.
What is calibration?
Article 3(9) of Vietnam’s Law on Measurement defines calibration as the activity of determining and establishing the relationship between the measured values of a measurement standard or measuring instrument and the values of the quantity to be measured. In practical terms, it provides evidence of how an instrument indicates relative to references under defined conditions. Source: Law on Measurement No. 04/2011/QH13, Government Portal.
A calibration result does not automatically mean “pass” for every intended use. A conformity statement requires an acceptance limit, a decision rule and appropriate treatment of measurement uncertainty. The equipment owner can then decide whether to continue use, adjust, repair or replace the instrument based on risk and applicable requirements.
ISO/IEC 17025:2017 is the international competence standard for testing and calibration laboratories. In Vietnam, the National Accreditation Bureau’s VILAS program uses ISO/IEC 17025 and field-specific supplementary requirements as accreditation criteria. Source: BoA—VILAS.
What is legal metrological verification?
Article 3(8) of the Law on Measurement defines verification as evaluating and confirming the metrological technical characteristics of a measuring instrument against metrological technical requirements. Its focus is a conclusion against applicable requirements, rather than calibration alone establishing a measurement relationship. Source: Law on Measurement, Official Gazette.
Do not assume that every measuring instrument has the same verification regime. Obligations depend on the instrument, its use and current sector rules. Where the governing requirement is unclear, check the current official list and instrument-specific provisions with the competent authority or a qualified provider.
Decree 105/2016/ND-CP and its amendments regulate conditions for organizations providing verification, calibration and testing of measuring instruments and measurement standards. Decree 36/2026/ND-CP, issued and effective on 23 January 2026, further amended that framework. Source: Official Gazette—Decree 36/2026/ND-CP.
What is inspection?
ISO/IEC 17020:2026 applies to bodies performing inspection. It covers competent, impartial and consistent examination of materials, products, installations, plants, processes, work procedures or services and determination of conformity with requirements. Those requirements can come from standards, regulations, contracts or internal specifications. Source: ISO—ISO/IEC 17020:2026.
In Vietnam, BoA’s VIAS program accredits inspection bodies against ISO/IEC 17020 and relevant ILAC requirements. Accreditation does not mean a body is competent for every inspection activity: buyers must check the current accredited scope. Source: BoA—VIAS.
Inspection under ISO/IEC 17020 must also be distinguished from measuring-instrument verification under the Law on Measurement and technical safety inspection under sector legislation. One provider may perform several services, but each requires the appropriate authority, competence, method and scope.
A practical decision path
- Start with the purpose: do you need measurement performance, a legally required confirmation, or conformity of an item against specified criteria?
- If you need values and deviations against references: consider calibration.
- If you need confirmation that a measuring instrument meets mandatory metrological requirements: identify the verification regime and an authorized organization.
- If you need an examination of a product, installation, process or service: consider inspection and the body’s relevant scope.
- If several regimes apply: you may need more than one activity; do not assume one document substitutes for another.
How to check a service provider
- Define the exact item, quantity, range, method, location and required capability.
- Check accreditation or designation status through an official source, not only a logo in a quotation.
- Confirm that the requested activity appears within a current scope.
- Agree acceptance criteria and the decision rule if a conformity statement is required.
- Request a sample report or certificate and review identification, results and conditions.
- Clarify subcontracting and which organization will issue each deliverable.
A company’s ISO 9001 certification does not replace technical competence accreditation under ISO/IEC 17025 or ISO/IEC 17020. Equally, accreditation applies only to the stated scope. The scope attachment—not the accreditation number alone—is essential evidence for purchasing decisions.
Frequently asked questions
Not by default. Calibration establishes a measurement relationship; verification evaluates and confirms against applicable metrological technical requirements. Determine the regime for the specific instrument before ordering.
No. Calibration results must be compared with defined acceptance criteria using an appropriate decision rule if a pass or fail conclusion is required.
No. ISO 9001 addresses a quality management system; ISO/IEC 17025 is used to assess the competence of testing and calibration laboratories.
Check the laboratory’s current accreditation status and scope through BoA, then compare the quantity, range, method and location with your requirement.
Include equipment identification, model, quantity and range, required points, work location, intended use, acceptance criteria, accreditation requirement and requested turnaround time.
Official sources used
- Law on Measurement No. 04/2011/QH13—Vietnam Government Portal
- Decree 36/2026/ND-CP—Official Gazette
- VILAS—National Accreditation Bureau
- VIAS—National Accreditation Bureau
- ISO/IEC 17020:2026—ISO
This is general information checked on 15 September 2026. Verify the current legal instrument and accreditation scope for each specific case.
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