Enter a Fahrenheit reading to find its Rankine temperature, or choose temperature difference for a rise or drop without adding the offset.
This is an absolute temperature. A result of 0 deg R is absolute zero.
Table of contents
How to use our Fahrenheit to Rankine Converter
- Choose "Measured temperature" for one thermometer, thermostat, equipment, or lab reading.
- Choose "Temperature difference" only for a rise, drop, change, or delta T between two temperatures.
- Enter one Fahrenheit value in the field shown, then click Calculate.
- Check the answer: 0 deg F equals 459.67 deg R, while a 20 deg F difference equals a 20 deg R difference.
Definitions
Measured temperature: One temperature reading, such as a thermometer reading or thermostat setting.
Temperature difference: How much temperature changes between two readings. A positive difference is a rise, and a negative difference is a drop.
Rankine (deg R): An absolute temperature scale with degree intervals the same size as Fahrenheit intervals.
Absolute zero: The lowest possible absolute temperature, equal to 0 deg R or -459.67 deg F.
Offset: The fixed 459.67 added to a measured Fahrenheit temperature. It is not used for a temperature difference.
Common mistakes and quick fixes
Mistake: Entering a temperature change as a measured temperature.
Fix: Choose "Temperature difference" for a rise, drop, change, or delta T. Do not add 459.67.
Mistake: Adding 459.67 to a 20 deg F difference.
Fix: A 20 deg F difference is a 20 deg R difference because the degree intervals are the same size.
Mistake: Entering a Celsius or Kelvin value in the Fahrenheit field.
Fix: Enter only a value labeled deg F, or convert the source value to Fahrenheit first.
Mistake: Entering a range such as "10 to 20" or a formula.
Fix: Enter one number. For a range, calculate each endpoint separately.
Mistake: Entering a measured temperature below -459.67 deg F.
Fix: Check the source and unit. A measured Rankine temperature cannot be below 0 deg R.
Limitations & Key Assumptions / Boundary Conditions
- Enter Fahrenheit values only; convert Celsius, Kelvin, or another temperature scale to Fahrenheit before using this calculator.
- Measured temperatures below -459.67 deg F are outside the Rankine scale and cannot be converted to a valid Rankine temperature.
- The calculator preserves useful decimal digits, but a converted result cannot be more precise than the original thermometer, sensor, or recorded value.
- A temperature difference gives the size and direction of a change. It does not provide the starting or ending temperature.
Methodology
Measured temperature
The calculator adds 459.67 to a measured Fahrenheit temperature. This places absolute zero at 0 deg R.
deg R = deg F + 459.67
For example, 68.5 deg F becomes 68.5 + 459.67 = 528.17 deg R.
Temperature difference
Fahrenheit and Rankine degree intervals have the same size, so a temperature change keeps the same number and sign. The absolute-temperature offset is not used.
deg R difference = deg F difference x 1
For example, a -5.5 deg F change is a -5.5 deg R difference. The calculator reports an offset of 0 for this conversion.
Calculation checks
Measured inputs below -459.67 deg F are rejected because they would produce a negative Rankine temperature. Zero is valid: 0 deg F converts to 459.67 deg R, and a 0 deg F difference converts to a 0 deg R difference.