Fahrenheit to Celsius
One °F equals -17.22222222 °C. Type any number and the answer appears as you type — the maths happens in your browser.
The same value in every unit
| Unit | Value |
|---|
- Free
- Files never leave your device
- No sign-up
Common values
| Fahrenheit | Celsius |
|---|---|
| -40 °F | -40 °C |
| -20 °F | -28.888889 °C |
| -10 °F | -23.333333 °C |
| 0 °F | -17.777778 °C |
| 10 °F | -12.222222 °C |
| 20 °F | -6.6666667 °C |
| 25 °F | -3.8888889 °C |
| 30 °F | -1.1111111 °C |
| 37 °F | 2.7777778 °C |
| 50 °F | 10 °C |
| 100 °F | 37.777778 °C |
| 200 °F | 93.333333 °C |
How to use
- Enter the number of Fahrenheit in the field.
- The result in Celsius updates on every keystroke.
- Use the table below for the values people look up most often.
Formula and reverse conversion
The formula
To convert by hand: °C = (°F − 32) × 5/9. Going back the other way, one °C is 33.8 °F.
Why you cannot just multiply
Celsius, Fahrenheit and Kelvin start counting from different points, so a temperature is converted with a formula rather than a factor. That is why −40 is the same number in Celsius and Fahrenheit, and why a difference between two temperatures converts differently from a temperature itself.
°C = (°F − 32) × 5/9
Frequently asked questions
How many Celsius are in one Fahrenheit?
One °F is -17.22222222 °C.
How do I convert Fahrenheit to Celsius?
Multiply by the factor: °C = (°F − 32) × 5/9.
Is the result exact?
The factors are the exact legal definitions, and up to ten significant digits are kept in the answer. Rounding happens only in the display.
How do I convert Celsius back to Fahrenheit?
One °C is 33.8 °F — or open the reverse page linked below.