Rankine scale
The Rankine scale is an absolute scale of thermodynamic temperature named after the Glasgow University engineer and physicist William John Macquorn Rankine, who proposed it in 1859. It is used in engineering systems where heat computations are done using degrees Fahrenheit.
The symbol for degrees Rankine is °R. By analogy with the SI unit, the kelvin, some authors term the unit rankine, omitting the degree symbol. 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 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 |
Absolute zero
| 0 K | −273.15 °C | −459.67 °F | 0 °R |
Freezing point of brine
| 255.37 K | −17.78 °C | 0 °F | 459.67 °R |
| Freezing point of water | 273.15 K | 0 °C | 32 °F | 491.67 °R |
| Boiling point of water | 373.1339 K | 99.9839 °C | 211.97102 °F | 671.64102 °R |
