measurand

The measurand is a physical quantity that is to be determined by the measurement. It is a function of the form Y = f(Xi), where Y stands for the displayed measured value and Xi for the input variable.

The measurand can be acquired directly via the measurement or calculated indirectly via mathematical relationships between two or more measured values, for example from a current and voltage measurement from which the power is calculated or via Ohm's law the resistance. The measurand can be constant in time, but it can also change in time.

InDIN 1319, the measurand is described as follows: Physical quantity to which the measurement applies. Measured quantity can be both the "measured quantity" and the "quantity to be measured". The measurand does not have to be the direct object of the measurement. When measuring physical quantities, the measurand has the dimension of the physical unit: volt, ampere, ohm, lux, power, etc. However, there are also dimensionless measurands such as angle specifications or refractive index.