Degree Rankine (°R)

ScientificTraditional unit (still used in some regions)

An absolute scale with Fahrenheit-sized degrees: 0 °R is absolute zero. Used in some engineering thermodynamics.

1 degree Rankine = 0.5555555556 kelvins (approximately).

About the degree Rankine

Scottish engineer and physicist William John Macquorn Rankine of the University of Glasgow proposed this scale in 1859. His idea was simple: keep the size of the Fahrenheit degree but start counting at absolute zero, so that no temperature is ever negative. Zero on the scale is therefore 0 K, which equals about minus 459.67 degrees Fahrenheit, and a reading in Rankine is just the Fahrenheit reading plus 459.67.

Because one Rankine degree is exactly 5/9 of a kelvin, converting is a matter of multiplying by 5/9 or, going the other way, multiplying kelvins by 9/5. NIST states the same relation as kelvin equal to the Rankine value divided by 1.8. Water freezes at 491.67 degrees Rankine and boils at roughly 671.64 degrees on the same scale. The scale appears mainly in some thermodynamics and heat-transfer calculations in US engineering, where data are tabulated in Fahrenheit-sized degrees. Everywhere else, kelvins and Celsius degrees have taken over, and the symbol is sometimes written °Ra to avoid confusion with the Rømer and Réaumur scales.

Sources: Wikipedia: Rankine scale; NIST SP 811, Appendix B.8 conversion factors

Degree Rankine conversion chart

100 degrees Rankine expressed in every other temperature unit:

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