Purposes of calibration of measuring instruments: - The purpose of calibration is to ensure that readings of an instrument are consistent with other instruments. It is also important in determining the accuracy of the instrument. - Calibration needed for evaluating and adjusting the precision and accuracy of measurement equipment. Instrument calibration is done to eliminate or reduce error in an instrument's readings. - Send the instrument for calibration after the test helps user decide whether the data obtained were reliable and correct or not. - If instrument is kept idle for a long time, the instrument's conditions will change, thus calibration in needed. - Every instrument will need to be calibrated periodically to make sure it can function properly and safely.