Verification vs Validation of Calibration Procedures/Methods

Procedure validation has long been a standard practice for calibration laboratories. However, the new revision of ISO/IEC 17025:2017 introduced the term ‘Verification’. In Clause, the standard states “The laboratory shall verify that it can properly perform methods before introducing them by ensuring that it can achieve the required performance. Records of the verification should be retained.”

Although the basic terminology was used in the ISO/IEC 17025:2005 version hidden in Clause 5.4.2, ‘The laboratory shall confirm that it can properly operate standard methods before introducing the tests or calibrations”, a bigger emphasis has been placed on the verification process and the documentation required.

What does this new term Verification mean and what is the difference between Verification and Validation?


Calibration laboratories sometimes use the terms Validation or Verification interchangeably, but they are not clear on the differences or the circumstances of when they are required to be used. Most of the confusion begins with the ISO 17025 standard definitions for the terms.

In ISO/IEC 17025:2005, Clause states that “Validation is the confirmation by examination and the provision of objective evidence that the particular requirements for a specific intended use are fulfilled.”

In the newer ISO/IEC 17025:2017, Verification is defined as “provision of objective evidence that a given item fulfills specified requirements’, while Validation is defined as ‘verification, where the specified requirements are adequate for an intended use”.

A large part of the new definition of Verification contains the same wording as the old definition of Validation. To begin to unravel the meanings of the words, we will begin with the method selection.

Method Selection

There are three basic types of methods/procedures that can be used in a calibration laboratory; standard methods, published procedures and laboratory-developed procedures.

Standard methods are methods published either in international, regional or national standards, or by reputable technical organizations, or in relevant scientific texts or journals.

Published procedures are procedures listed in other published outlets and include manufacturer’s performance tests in manufacturer service manuals and military procedures through GIDEP.

Laboratory-developed procedures are procedures written within an individual calibration laboratory, typically when the information required is not available in the documents listed above.

For most calibration laboratories, the standard methods are not used as procedures. Standard publications such as ASME, ANSI, ISO, etc. have specific information on equipment classifications and specifications, but they typically do not contain true calibration procedures. These methods are directed more towards testing laboratories rather than calibration laboratories. For the majority of calibration laboratories, either published procedures or laboratory-developed procedures are used.


Standard methods and published procedures are considered to be validated. That means that the method/procedure has been proven to produce the stated measurement results when the procedure is properly followed.

However, every calibration laboratory has different equipment, competencies, and other factors that will determine what capabilities the laboratory can maintain.

Due to this, “Verification” is required for these methods/procedures to show that the laboratory is capable of performing the procedure and are able to achieve the measurement values, accuracy and other performance parameters of the procedure.

The Verification needs to be documented and the procedure should be verified to ensure that the laboratory has the required:

Equipment – The equipment used for the calibration should be equivalent in accuracy and scope as the recommended equipment in the procedure.

Environmental Conditions – The laboratory should have the proper environmental conditions for the performance of the procedure.

Personnel Competence – The personnel assigned to perform the procedure should have the necessary training and experience for the calibration.


If a new procedure is used that has just been developed by the laboratory, a “Validation” is required to show that the procedure is capable of being performed and can meet the required specifications.

Validations are required for all new procedures or previously validated procedures that require revisions because they’ve been significantly changed. A ‘re-validation’ would be required if significant changes were made to the procedure methodology, equipment used in the procedure, specification or environmental changes, or other conditions that could affect the results. This includes any of the standard methods or published procedures listed above if there are significant changes in how the calibration laboratory is performing the procedure.

If changes are made to a specific section of a previously validated procedure, only that section would need to be re-validated.

The extent of the Validation should be developed with consideration of the costs, risks, customer requirements, and the intended use of the results.

The Validation documentation for the procedure should identify that the:

Proper equipment is listed – The equipment should be able to perform the calibration steps in the procedure.

Correct measurement values in tables or data forms – The calculated measurement values from the equipment specifications should be correct.

Calibration setup and connections are correct – Any diagrams or descriptions of the setup of the equipment needs to be correct.

Procedure steps produce the desired measurement outcome – The measurement values obtained during the validation should be what is required in the procedure.

It is important that the individual who wrote the procedure should not be the person who validates the procedure. A bias can be introduced if the same person performs the validation. The validation should be performed by another competent technician certified in the discipline of the piece of equipment the validation is being performed for.


To summarize, for a “Verification”, the emphasis is on the calibration laboratory to ensure that it can perform a standard or published procedure, whereas in a “Validation”, the emphasis is that the procedure being validated can produce the required measurement results.