Calibration

Measuring tools, such as this balance, need to be calibrated, to give exact results.

When doing measurements using a device or tool, it is important to know that this measurement has as little error as possible. There is a process, known as calibration. It consists of doing some measurements, where the outcomes are known, and comparing the mesurements of the device under test with the known values. In many cases, the device under test can then be adjusted to correct these errors. To be able to do accurate measurements, a decice needs to be calibrated regularly.

The reasons to do a calibration include the following:

• The device is new, and has not been used before
• The device has been repaired, or modified
• The device is used at a different location.
• After a specified time period has elapsed. Devices need to be calibrated periodically, to stay accurate
• After the device has been in use for a long time.
• Before or after an important or critical measurement
• When the measurements look counterintuitive, or odd; or when they don't match those of other similar devices close by

In general, calibration includes the process of adjusting the output or indication on a measurement instrument to agree with value of the applied standard, within a specified accuracy. That way, a balance or thermometer can be corrected to show the exact value.