Temperature Converter
Convert Celsius, Fahrenheit, Kelvin, and Rankine.
Enter a value, choose the units, and see the result plus every other temperature unit.
Celsius → Fahrenheit
Temperature Converter
Convert temperatures between Celsius, Fahrenheit, Kelvin, and Rankine, plus the historic Réaumur, Delisle, Newton, and Rømer scales. Unlike most units, temperature scales have different zero points, so the converter applies a full formula instead of a simple multiplication.
Formulas
| From → To | Formula |
|---|---|
| °C → °F | °F = °C × 9/5 + 32 |
| °F → °C | °C = (°F − 32) × 5/9 |
| °C → K | K = °C + 273.15 |
| °F → °R | °R = °F + 459.67 |
Because of the offset, doubling a Celsius value does not double the Fahrenheit value: 10 °C is 50 °F, but 20 °C is 68 °F.
Reference points
| Event | °C | °F | K |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Water boils (sea level) | 100 | 212 | 373.15 |
Cooking and weather examples
American recipes often say "bake at 350 °F", which is 176.67 °C – most European ovens are simply set to 180 °C, which is 356 °F. A weather forecast of 20 °C is a mild 68 °F, or 293.15 K in a physics lab.
Historic scales
The converter also handles scales you may meet in old texts or trivia. At the boiling point of water, the Réaumur scale reads 80 °Ré, the Newton scale 33 °N, the Rømer scale 60 °Rø, and the Delisle scale 0 °De – Delisle counts downward, so water freezes at 150 °De.
Tips
Negative inputs work normally, so you can check freezer or winter temperatures. Temperature differences (for example "a rise of 10 degrees") convert without the offset: a change of 10 °C is a change of 18 °F. For related engineering quantities, see the Energy Converter and the Pressure Converter.
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 (1.8) and add 32. For example, 37 °C × 1.8 + 32 = 98.6 °F. To go back, subtract 32 and multiply by 5/9.
At what temperature are Celsius and Fahrenheit equal?
At −40 degrees. −40 °C is exactly −40 °F, the only point where the two scales meet.
Why is there no degree sign on Kelvin?
Kelvin is an absolute SI unit, so it is written simply as K (for example 293.15 K). 0 K is absolute zero, equal to −273.15 °C or −459.67 °F.
What is the Rankine scale?
Rankine is an absolute scale that uses Fahrenheit-sized degrees. 0 °R is absolute zero and water freezes at 491.67 °R. It is still used in some US engineering thermodynamics.