Convert Fahrenheit to Celsius in one step. Type a value, change the units if you need a different pair, and the answer updates as you type, with the reverse rate and a quick reference list.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How to convert Fahrenheit to Celsius
The two scales have different zero points, so a single multiplier will not work. Use the formula:
°C = (°F − 32) × 5 ÷ 9
Kelvin equals Celsius plus 273.15. The converter works in Celsius internally and then converts to the unit you choose, so it handles any pair of the three scales.
Worked example
Using the default values in the converter above:
| Input | Value |
|---|---|
| Value | 68 |
| From | Fahrenheit |
| To | Celsius |
68 Fahrenheit equals 20 Celsius
Fahrenheit to Celsius reference table
| Fahrenheit | Celsius |
|---|---|
| -40 °F | -40 °C |
| -10 °F | -23.333333 °C |
| 0 °F | -17.777778 °C |
| 10 °F | -12.222222 °C |
| 20 °F | -6.666667 °C |
| 30 °F | -1.111111 °C |
| 37 °F | 2.777778 °C |
| 100 °F | 37.777778 °C |
| 180 °F | 82.222222 °C |
Tips and common mistakes
Celsius and Fahrenheit do not start at the same point, so you cannot convert with a single multiplier. The formulas are °F = °C × 9 ÷ 5 + 32 and °C = (°F − 32) × 5 ÷ 9. Kelvin is Celsius plus 273.15 and has no negative values.
A handy check is that -40 is the same on both scales. For rough mental maths going from Celsius to Fahrenheit, double the number and add 30: it is close enough for weather, but not for cooking or science.
Common mistakes are forgetting the 32 offset, or multiplying by 5 ÷ 9 before subtracting 32 when converting to Celsius. The converter refuses values below absolute zero (-273.15 °C) because they cannot exist.
Frequently asked questions
What is 0 °F in °C?
0 °F is -17.777778 °C.
How do I convert °F to °C by hand?
Use °C = (°F − 32) × 5 ÷ 9. For example, 68 °F is 20 °C.
At what temperature are Celsius and Fahrenheit equal?
At -40. The two scales give the same number at that point.
What is absolute zero?
Absolute zero is 0 kelvin, -273.15 °C or -459.67 °F, the coldest temperature that is physically possible. The converter does not accept values below it.