Editing Thermodynamic temperature (section)

== Rankine scale ==
{{main|Rankine scale}}
Though there have been many [[Conversion of units of temperature|other temperature scales]] throughout history, there have been only two scales for measuring thermodynamic temperature which have absolute zero as their null point (0): The Kelvin scale and the Rankine scale.

Throughout the scientific world where modern measurements are nearly always made using the International System of Units, thermodynamic temperature is measured using the Kelvin scale. The Rankine scale is part of [[English Engineering Units|English engineering units]] and finds use in certain engineering fields, particularly in legacy reference works. The Rankine scale uses the ''degree Rankine'' (symbol: °R) as its unit, which is the same magnitude as the [[Fahrenheit|degree Fahrenheit]] (symbol: °F).

A unit increment of one kelvin is exactly 1.8 times one degree Rankine; thus, to convert a specific temperature on the Kelvin scale to the Rankine scale, {{nowrap|1='''{{math|''x''}} K = 1.8 {{math|''x''}} °R'''}}, and to convert from a temperature on the Rankine scale to the Kelvin scale, {{nowrap|1='''{{math|''x''}} °R = {{math|''x''}}/1.8 K'''}}. Consequently, absolute zero is "0" for both scales, but the melting point of water ice (0&nbsp;°C and 273.15&nbsp;K) is 491.67&nbsp;°R.

To convert temperature ''intervals'' (a span or difference between two temperatures), the formulas from the preceding paragraph are applicable; for instance, an interval of 5 kelvin is precisely equal to an interval of 9 degrees Rankine.