Rankine (°R) to Kelvin Converter

About this calculator

The Rankine scale is an absolute temperature scale — like Kelvin, its zero point is absolute zero — but it uses Fahrenheit-sized degrees instead of Celsius-sized ones. The conversion is simply K = °R × 5/9 (the same 5/9 ratio that relates Fahrenheit degrees to Celsius degrees), so water's freezing point, 491.67°R, converts to 273.15 K.

US aerospace, mechanical, and HVAC engineers working in Fahrenheit-based unit systems still use Rankine in thermodynamic calculations — ideal gas law, combustion, and compressible-flow equations that require an absolute temperature — specifically because it lets them keep every other measurement in familiar Fahrenheit-based units while still satisfying the "temperature must be absolute" requirement those formulas demand.