# Rankine scale

The Rankine scale (/ˈræŋkɪn/) is an absolute scale of thermodynamic temperature named after the Glasgow University engineer and physicist William John Macquorn Rankine, who proposed it in 1859. (The Kelvin scale was first proposed in 1848.)[1] It may be used in engineering systems where heat computations are done using degrees Fahrenheit.

Rankine
Unit ofTemperature
Symbol°R, °Ra
Named afterWilliam John Macquorn Rankine

The symbol for degrees Rankine is °R[2] (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). By analogy with Kelvin, some authors term the unit Rankine, omitting the degree symbol.[3][4] Zero on both the Kelvin and Rankine scales is absolute zero, but a temperature difference of one Rankine degree is defined as equal to one Fahrenheit degree, rather than the Celsius degree used on the Kelvin scale. Thus, a temperature of 0 K (−273.15 °C; −459.67 °F) is equal to 0 °R, and a temperature of −458.67 °F equal to 1 °R.

Some important temperatures relating the Rankine scale to other temperature scales are shown in the table below.

Kelvin Celsius Fahrenheit Rankine 0 K −273.15 °C −459.67 °F 0 °R 255.37 K −17.78 °C 0 °F 459.67 °R 273.15 K 0 °C 32 °F 491.67 °R 373.1339 K 99.9839 °C 211.97102 °F 671.64102 °R

## Notes

1. The ice point of purified water has been measured to be 0.000089(10) degrees Celsius – see Magnum 1995
2. For Vienna Standard Mean Ocean Water at one standard atmosphere (101.325 kPa) when calibrated solely per the two-point definition of thermodynamic temperature. Older definitions of the Celsius scale once defined the boiling point of water under one standard atmosphere as being precisely 100 °C. However, the current definition results in a boiling point that is actually 16.1 mK less. For more about the actual boiling point of water, see VSMOW in temperature measurement.

## References

1. "Rankine". Merriam-Webster Dictionary. Retrieved 2019-11-07.
2. Pauken 2011, p. 20
3. Balmer 2011, p. 10