Calibration or adjustment – what’s the difference?

If your metrology equipment has been calibrated and the results show the device is out of tolerance, then it’s likely to need an adjustment.

But where does a calibration end and an adjustment begin? What’s the difference between the two processes? And why are adjustments not always necessary if a device is out of tolerance?

Read on for the answers to these commonly asked questions:

What is a calibration?

Put simply, a calibration will tell you how accurate your device is in its current state.

Calibrations are critical for devices used within manufacturing environments as the conditions they are subjected to can cause incremental changes to the readings on the device – eventually pushing it out of tolerance and making readings inaccurate.

To ensure that your device remains accurate it’s important to have it calibrated regularly (for more information on this, read our blog article on managing and optimising metrology equipment calibrations).

What happens during a calibration?

A calibration is a documented comparison of the measurement device to be calibrated against a traceable reference device.

During the calibration process, readings will be taken from various points over the measuring range of the device. The results from your device will be compared against a traceable reference device with a higher level of accuracy than the device under test.

If the deviation of the item reading is within the manufacturer’s specifications, a calibration certificate will be issued which provides details of the test and proves the item has been calibrated.

If the device falls out with the manufacturer’s specifications, then it may need to be adjusted.


When would I need an adjustment?

Contrary to popular belief, a calibration and an adjustment are two separate processes.

Strictly speaking, the term ‘calibration’ is purely the act of comparison between a device and a known ‘traceable’ standard (otherwise known as calibration equipment).

An adjustment is performed as an additional step to bring the device back within its specified tolerances and will only be carried out if the deviation is found to be too high during a calibration.

Why an adjustment is not always the answer

In some situations, even if a device is out of tolerance an adjustment still isn’t the best option.

If your device falls hugely out of tolerance, it can be more cost effective to replace the equipment rather than carry out a complex adjustment.

Some companies choose to continue to use their equipment out of tolerance and make allowances for this by calibrating to their own specifications, rather than the manufacturer’s specifications. This would be discussed when the item is due for calibration to ensure the testing carried out takes the higher tolerance levels into account.

We’re here to help

Calibrate your metrology equipment with us and our team will keep you informed throughout each stage of the process. If the results of a calibration show your device is out of tolerance, our experts will be straight in touch to discuss the best option for you.