Real versus nominal value (metrology)

For the distinction between real purchasing power and nominal value, see Real versus nominal value (economics).

The distinction between real value and nominal value occurs in many fields. In metrology, the nominal value of a physical quantity is a rounded or approximate value, useful as a guidance for the appropriate use of an object under consideration. From a philosophical viewpoint, nominal value represents an accepted condition, which is a goal or an approximation, as opposed to the real value, which is assumed always present.