What is the difference between calibration, adjustment, and verification?

In technical fields, the terms “calibration,” “adjustment,” and “verification” are often used interchangeably. However, they all have different meanings. We explain the differences.

Calibration

Calibration is the process of comparing a measuring instrument with a reference standard without making any changes to it. You determine the magnitude of the deviation between the instrument’s reading and the actual value.

The result is a calibration certificate or calibration report detailing the measured deviations.

Adjustment

Adjustment is the process of fine-tuning or correcting a measuring instrument so that it measures as accurately as possible. This is usually done after calibration, when it becomes apparent that the deviation is too large. You adjust the instrument mechanically, electrically, or via software.

The logical sequence is therefore:

1. Calibrate to determine the deviation
2. Adjust, if necessary, to correct this deviation
3. Recalibrate to verify the result

Verification

Verification is an official, legally regulated process in which an authorized body (in Belgium, the FPS Economy – Metrology Service) determines whether a measuring instrument meets legal requirements. If the instrument is approved, it receives a verification mark (stamp or seal).

Verification is mandatory for devices used in commercial transactions or where consumer protection is required, such as:

• scales in stores
• gas pumps
• taximeters
• water meters, gas meters, electricity meters

The differences

In short: you calibrate to determine how accurately a device measures, you adjust it to improve its measurement accuracy, and you certify it to legally prove that it meets the standards.