Fahrenheit to Celsius
Convert Fahrenheit to Celsius — type a temperature in either box. The formula is °C = (°F − 32) × 5/9.
How to use
- Enter a temperature in the Fahrenheit field.
- The Celsius value updates instantly.
- Negative values work exactly the same way.
- Check the reference table for the fixed points.
Fahrenheit 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 = (°F − 32) × 5/9
Work left to right through the formula and the result will be correct for any input, including negatives.
Worked example
Converting 20 °F gives -6.67 °C.
20 °F → -6.67 °C
Reference points
Four temperatures worth memorizing, in both scales:
| Reference point | Fahrenheit | Celsius |
|---|---|---|
| water freezing | 32 °F | 0 °C |
| a mild room | 68 °F | 20 °C |
| body temperature | 98.6 °F | 37 °C |
| water boiling | 212 °F | 100 °C |
What is a degree Fahrenheit?
Fahrenheit is the everyday temperature scale in the United States, with water freezing at 32 °F and boiling at 212 °F.
Definition: Defined against Celsius: °F = °C × 9/5 + 32. The 180-degree span between freezing and boiling gives it finer granularity than Celsius.
Where it is used: US weather, cooking, oven settings and body temperature.
Worth knowing: The two scales cross at −40°, where −40 °C and −40 °F are the same temperature.
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 Fahrenheit to Celsius?
Use °C = (°F − 32) × 5/9.
What is 0 °F in Celsius?
0 °F is -17.78 °C.
What is 100 °F in Celsius?
100 °F is 37.78 °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 fahrenheit?
The two scales cross at −40°, where −40 °C and −40 °F are the same temperature.
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.