Rankine is a thermodynamic (absolute) temperature scale named after the Scottish engineer and physicist William John Macquorn Rankine, who proposed it in 1859.
The symbol for degrees Rankine is °R (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). Zero on both the Kelvin and Rankine scales is absolute zero, but the Rankine degree is defined as equal to one degree Fahrenheit, rather than the one degree Celsius used by the Kelvin scale. A temperature of −459.67 °F is exactly equal to 0 °R.
Some engineering fields in the U.S. and Canada measure thermodynamic temperature using the Rankine scale. However, throughout most of the scientific world thermodynamic temperature is measured in Kelvin. The US National Institute of Standards and Technology does not recommend using degrees Rankine in NIST publications.
Some key temperatures relating the Rankine scale to other temperature scales are shown in the table below.
Conversion table between the different temperature units
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