Real versus nominal value

The distinction between real versus nominal value occurs in many fields.

[edit] Engineering

In various subfields of engineering, a nominal value is one which where the "name" for the value is close to, but not the same as, the actual value. Some examples:

• For dimensional lumber in North America, a "two by four" is not 2 inches by 4 inches, but rather 1½ in × 3½ in.
• Mains electricity is nominally 230 V in the European Union, but is allowed to vary ±10%. In North America, the nominal voltage is 120 V, with variance allowed from 114 V to 126 V (±5%).
• NiMH and NiCd rehargable batteries have a nominal voltage of 1.5 V, but actually supply 1.25 V.
• 56 kbit/s modems cannot exceed 53.3 kbits/second.

Other cases involve diameter, speed, and volume.

Sometimes the word "nominal" is also used in engineering contexts as a synonym for "normal".

[edit] Economics

Main article: Real versus nominal value (economics)

In economics, "nominal" values are the "face value" of currency over long periods of time (years), whereas "real" values have been corrected for inflation.