# Rankine scale

Rankine temperature conversion formulae
from Rankine to Rankine
Celsius [°C] = ([°R] − 491.67) × ​59 [°R] = ([°C] + 273.15) × ​95
Fahrenheit [°F] = [°R] − 459.67 [°R] = [°F] + 459.67
Kelvin [K] = [°R] × ​59 [°R] = [K] × ​95
For temperature intervals rather than specific temperatures,
1 °R = 1 °F = ​59 °C = ​59 K
Comparisons among various temperature scales

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.

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.

The US National Institute of Standards and Technology recommends against using the degree symbol when citing Rankine in NIST publications.[2]

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 273.16 K 0.01 °C 32.018 °F 491.688 °R 373.1339 K 99.9839 °C 211.97102 °F 671.64102 °R