Imperial Unit of temperature which measures 0 °R at absolute zero and 491.688 °R at water triple point.
It is related to a more common in engineering practise Fahrenheit unit (°F) as: T [°R] = T [°F ] + 491.688
It is related to Kelvin unit (°K) as: T [°R] = 1.8 · T [°K]
See also