Page "Calibration curve" Paragraph 3

In more general use, a calibration curve is a curve or table for a measuring instrument which measures some parameter indirectly, giving values for the desired quantity as a function of values of sensor output.

For example, a calibration curve can be made for a particular pressure transducer to determine applied pressure from transducer output ( a voltage ).

Such a curve is typically used when an instrument uses a sensor whose calibration varies from one sample to another, or changes with time or use ; if sensor output is consistent the instrument would be marked directly in terms of the measured unit.