Rankine is a temperature scale that, like kelvin, sets zero at absolute zero, but uses Fahrenheit degrees. A difference of 1 degree R. is equal to a difference of 1 degree F, but absolute zero is 0 degrees R, or -459.67 degrees F. Thus:
To convert from Fahrenheit to Rankine, add 459.67.
To convert from Rankine to Fahrenheit, subtract 459.67.
To convert from kelvin to Rankine, multiply by 1.8.
To convert from Rankine to kelvin, divide by 1.8.