The symbol is °R (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). As with the Kelvin scale (symbol: K), zero on the Rankine scale 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 precisely equal to 0 °R.
A few engineering fields in the U.S. measure thermodynamic temperature using the Rankine scale. However, throughout the scientific world where measurements are made in SI units, thermodynamic temperature is measured in
Some key temperatures relating the Rankine scale to other temperature scales are shown in the table below.
^ The ice point of purified water has been measured to be 0.000089(10) degrees Celsius - see Magnum, B.W. (June 1995). "Reproducibility of the Temperature of the Ice Point in Routine Measurements" (PDF). Nist Technical Note1411. Retrieved on 2007-02-11.
^ 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.