Rankine to Celsius
Convert Rankine to Celsius — type a temperature in either box. The formula is °C = (°R − 491.67) × 5/9.
How to use
- Enter a temperature in the Rankine field.
- The Celsius value updates instantly.
- Negative values work exactly the same way.
- Check the reference table for the fixed points.
Rankine to Celsius formula
Temperature is the one conversion that needs more than a multiplication: the scales disagree about where zero sits, so an offset is required as well as a ratio.
°C = (°R − 491.67) × 5/9
The order of operations matters: follow the formula exactly as written above.
Worked example
Converting 37 °R gives -252.59 °C.
37 °R → -252.59 °C
Reference points
Four temperatures worth memorizing, in both scales:
| Reference point | Rankine | Celsius |
|---|---|---|
| water freezing | 491.67 °R | 0 °C |
| a mild room | 527.67 °R | 20 °C |
| body temperature | 558.27 °R | 37 °C |
| water boiling | 671.67 °R | 100 °C |
What is a degree Rankine?
Rankine is an absolute temperature scale that uses Fahrenheit-sized degrees, starting at absolute zero.
Definition: 0 °R is absolute zero and one degree Rankine equals one degree Fahrenheit, so °R = °F + 459.67.
Where it is used: US thermodynamics and aerospace engineering, where absolute temperature is needed but Fahrenheit degrees are the working convention.
What is a degree Celsius?
Celsius is the everyday temperature scale in nearly every country, with 0 °C at water's freezing point and 100 °C at its boiling point.
Definition: Now defined from the kelvin: a temperature in °C equals the kelvin value minus exactly 273.15. Since 2019 the kelvin itself is fixed by the Boltzmann constant.
Where it is used: Weather forecasts, cooking, medicine and science worldwide outside the United States.
Worth knowing: A degree Celsius and a kelvin are the same size, so a temperature difference is numerically identical in both — only absolute readings differ.
Frequently asked questions
What is the formula to convert Rankine to Celsius?
Use °C = (°R − 491.67) × 5/9.
What is 0 °R in Celsius?
0 °R is -273.15 °C.
What is 100 °R in Celsius?
100 °R is -217.59 °C.
Does this work for negative temperatures?
Yes. The formula is linear, so it is valid above and below zero on either scale.
Is there anything to watch out for with celsius?
A degree Celsius and a kelvin are the same size, so a temperature difference is numerically identical in both — only absolute readings differ.