What is the key difference between Calibration and Verification?

It is not our differences that divide us. It is our inability to recognize, accept and celebrate those differences: Audre Lorde


Is there any difference between ‘advice and advise’ or ‘principle and principal’ or ‘there and their’? Although the spelling seems to be similar, each word has its unique meaning, purpose and intent. The understanding of the differences brings us closer to the fact.


For any organization, both calibration and verification are important activities. They have their unique purpose and are being conducted as per the requirement of the test equipment. The clarity between the two helps the organization and user to implement them effectively for all gauges and measuring & test equipments (Employee / Customer / Onsite supplier- owned equipments).

Definitions: ISO 9000: 2015

Verification (Cl 3.8.12): Confirmation through the provision of objective evidence that specified requirements have been fulfilled.

Calibration: It is the process of comparing an unknown quantity or value to a known quantity. A trained calibration technician will check the instrument at several points through its range and may make adjustments to align the instrument with the standard if it is found to be out of tolerance.

Detailed Information

Calibration and Verification are mostly used interchangeably if you are not aware of their differences and true meaning. Both have their distinct meaning and purpose. Depending on the requirements, the organization decides whether to calibrate or verify the test equipment.

As per Clause of ISO 9001 and IATF 16949, there are certain guidelines for conducting calibration and verification.

Why do Calibration or Verification?

  • To know the actual status of the measuring instrument
  • To know whether the accuracy of the measurement system
  • To know whether the resulting output coming from the measuring instrument can be relied on or not

Key difference between Calibration and Verification:

S.No. Calibration Verification
1 A calibration indicates the error of the instrument  Process of “confirming” that a given specification is fulfilled
2 Is it accurate? Is it working correctly?
3 Compensates for any lack of trueness by applying a correction A simple check to confirm that a certain instrument or equipment meets the intended output basing it to the requirements of certain specifications.
4 The “comparison” of the unknown reading of a Unit Under Calibration (UUC) to a known reading of a Reference Standard, also known as the Master. not a comparison to a higher standard

The objective is guided by specifications from:

-a legal or regulatory body, examples are ASTM and ISO

-Manufacturer requirements

-process or user requirements

5 Calibration is conducted for the entire working range of the instrument like Vernier calliper (0 – 200 mm): 20, 50, 80, 100, 120, 150, 200 mm. Not checking the entire range. Just only to ensure that it is acceptable on its working or intended range


6 Can determine the accuracy and error or how far is the reading to the true value. Ensuring that the instrument is working correctly for its intended purpose
7 The traceability, the unbroken chain of comparison linking to the highest level (International standard like NIST or National Standard like NPL) Not required to check the traceability with International or National Standard
8 Computed Measurement Uncertainty


Process of comparison between actual measurement results, and the published specification for the unit under test.
9 Based on the result, pass or failed decisions are decided by the user as per their process acceptance criteria. Verification is simply used to discover if an instrument is still measuring to within specification

Present Challenges:

  • How often in-house calibration is conducted by competent manpower?
  • How often inhouse calibration is conducted by following specified environment conditions like temperature, humidity?
  • How often the rule of 1/10th is understood and following while calibration?


ISO 9000: 2015

ISO 9001: 2015

IATF 16949: 2016

ISO 10012: 2003

ISO 17025: 2017

Industry Experts

This is the 102nd article of this Quality Management series. Every weekend, you will find useful information that will make your Management System journey Productive. Please share it with your colleagues too.

Your genuine feedback and response are extremely valuable. Please suggest topics for the coming weeks.

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Ramveer Singh
Ramveer Singh
1 year ago

I have 5yr experience in pharma company. But not fluent speak any manager and hod nor plant head . But why sir . I have no confidence any questions and answer. Really I’m so sad .