Converting Fahrenheit to Rankine
Rankine is an absolute temperature scale while Fahrenheit is a relative scale but they have the same degree increments. Because of this converting Fahrenheit to Rankine is very easy... simply add 459.67.
For example, suppose you want to convert 68 degrees F. You would add 459.67 to get the equivalent temperature in Rankine making which is 527.67 degrees R.
The Rankine scale is hardly ever used in everyday life as the Fahrenheit scale is more popular. However, in certain fields such as aerospace or materials science the Rankine scale may be used to work with absolute temperature values.
About the Fahrenheit scale
Fahrenheit is a relative temperature scale created by the Polish-German physicist Daniel Gabriel Fahrenheit. It is mainly used in the United States and is less common in science compared to the Celsius (or Centigrade) scale.
Fahrenheit is based on the freezing and boiling points of water at standard atmospheric pressure with 32°F at freezing point and 212°F at boiling point.
Whilst Fahrenheit is still commonly used in the United States it is important to note that most of the world relies on Celsius.
About Rankine
Rankine is temperature unit normally used in thermodynamics. It is named after the Scottish engineer and physicist William John Macquorn Rankine, who is know for his work in thermodynamics. The Rankine scale is based on the Fahrenheit scale with degree increments identical but starting at absolute zero.
With the zero point at absolute zero (-459.67°F) it is easy to convert between Rankine and Fahrenheit: simply subtract 459.67.
The Rankine scale is not normally used in everyday life as it is an engineering unit particularly thermodynamics in the United States.