Measurement instruments are usually calibrated annually, people/companies do this because it is easy to schedule. This may not necessarily be the best approach to take, most test instruments will drift over time, the newer the instrument the more frequently it needs to be calibrated, until its ability to reproduce measurements over a period of time has been established and is well understood. A user might estimate a suitable recalibration frequency, based on previous experience of similar instruments used in similar environments, but it is only when the actual data from a series of successive calibrations of a particular instrument has been properly analysed that a meaningful recalibration frequency can be determined for that particular instrument.

To provide confidence in the validity of the test equipment calibration results they must be traceable. This means the results on the instrument(s) calibration certificate need to be traceable to the standard used, and the results on the certificate for the standard are in turn traceable to the standard used for its calibration.

Not necessarily, but if your test equipment isn’t measuring accurately then you won’t receive correct measurement readings. Calibrations can be costly and that is one of the main factors when it comes to deciding not to calibrate your instrument(s). However, there can be even bigger costs when it comes to using an un-calibrated instrument such as product re-calls, how does the cost of a product recall stack up against the cost of calibrating an instrument(s).