What is the difference between Accreditation and Certification?


The recent changes to ISO 9001:2015 have caused some confusion about how to select a calibration provider.

Does a calibration provider need 

ISO 9001 certification


ISO 17025 accreditation?

Or both?

What is the difference?


ISO 9001 never has and still does not address technical competence. A key distinction between ISO 17025 and ISO 9001 is technical competence. In order to obtain ISO 17025 accreditation a laboratory MUST have a management system that meets the principles of ISO 9001.

This is clearly stated in the introduction: " Testing and calibration laboratories that comply with this International Standard will therefore also operate in accordance with ISO 9001."

While the 2015 revision does address risk management and that certainly includes calibration, it does not address critical areas of technical competence.

These would include:Traceability_Pyramid.jpg

  • Staff Qualifications
  • Equipment
  • Environment
  • Methods
  • Traceability
  • Measurement Uncertainty


ISO 17025 accreditation goes past just having a quality management system. As a consumer of calibration, one way to access technical competence is to look at the Scope of Accredited services.

The "Scope" articulates what parameters the laboratory has demonstrated technical competence. This is typically shown as the major headings such as " Electrical- Capacitance" or "Length-Hand Tools and Precision Gages". The subheadings would then call out common terms such as caliper, micrometer, Capacitance-source, etc. Specificity of competence is then drilled down by the range of demonstrated competence.

When comparing Scopes of Accredited services, different laboratories may both be accredited for calipers. One may have a range of 0-60 inches while the other has a range of 0-120 inches. This is important to know because one laboratory has demonstrated competence across a broader range. This does not necessarily mean that one laboratory is better or worse than the other.


The Scope will also include Expanded Measurement Uncertainty. It is critical that the consumer of calibration services understands what this means. In simplest terms, this is the +/- in a measurement. This really speaks to the suitability/capability of a laboratory to provide you with a meaningful calibration. For example, two laboratories may be accredited for Thermometers. One has a measurement uncertainty of 0.12◦C while the other has 1.0◦C. As a consumer of calibration services, you need to know this to determine which laboratory is capable of providing the calibration best suited for your specific needs. Just because a laboratory is ISO 17025 accredited does not mean they are capable of providing the calibration you need.

As pointed out above ISO 9001 does not provide any evidence that a laboratory can provide you with accurate and reliable calibration.


We hope we didn't lose you in the weeds! ILAC- The International Laboratory Accreditation Cooperation has an excellent resource you may want to read.


Download the FREE ILAC Brochure Certification or Accreditation 

Still, have questions? Please feel free to ask us.


Visit our International Standards used in Calibration page for more on standards used in calibration.

Phil Wiseman

Phil Wiseman

Phil Wiseman is Chief Marketing Officer at Alliance Calibration. He earned a B.S. in Chemical Physics from Centre College. Phil is an ASQ Certified Quality Auditor and ASQ Certified Manager of Quality/Organizational Excellence.

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