Temperature converter
Convert Celsius, Fahrenheit, Kelvin and Rankine. Each answer shows the offset step, because that is the step people get wrong.
Common temperature conversions
Not sure which unit you need?
Read the temperature unit guide — what each one is, where it came from, and which of them are quietly different from each other.
Every temperature unit
| Unit | Symbol | In degrees Celsius |
|---|---|---|
| Degrees Celsius | °C | 1 |
| Degrees Fahrenheit | °F | 0.55555556 − 17.777778 |
| Kelvin | K | 1 − 273.15 |
| Degrees Rankine | °R | 0.55555556 − 273.15 |
Questions
Why can't I just multiply to convert Celsius to Fahrenheit?
Because the two scales do not start in the same place. Zero Celsius is 32 Fahrenheit, so you have to shift as well as scale: multiply by 9/5, then add 32. Multiplying alone is right only for a temperature difference, never a temperature.
Where do the two scales meet?
At −40. Minus forty Celsius and minus forty Fahrenheit are the same temperature, which is the one value you can quote in either scale without converting.
Is it 'degrees Kelvin'?
No. Kelvin is written without the degree sign and without the word degree — 300 K, read as three hundred kelvin. It is an absolute scale, so there is no offset to name.
What is Rankine for?
Rankine is Fahrenheit's absolute scale: same size step, but starting at absolute zero instead of the Fahrenheit zero. It still turns up in US thermodynamics and aerospace work.