How to Convert Celsius to Fahrenheit (and Back)
The exact formula for converting Celsius to Fahrenheit and back, why temperature conversion needs an offset instead of just a multiplier, and worked examples.
To convert Celsius to Fahrenheit: multiply by 9/5, then add 32. To go the other way, subtract 32 first, then multiply by 5/9. Unlike most unit conversions, temperature needs both a scale factor and an offset, because the two scales don't share a zero point.
The formulas
°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
Worked examples
| Celsius | Calculation | Fahrenheit |
|---|---|---|
| 0°C | (0 × 9/5) + 32 | 32°F (freezing point of water) |
| 100°C | (100 × 9/5) + 32 | 212°F (boiling point of water) |
| 37°C | (37 × 9/5) + 32 | 98.6°F (average body temperature) |
| 20°C | (20 × 9/5) + 32 | 68°F (room temperature) |
Why you can't just multiply
A simple multiplier works when two scales share a zero point — 0 inches is always 0 centimeters. But 0°C is not 0°F; it's 32°F. Skipping the +32 offset is the most common temperature-conversion mistake, and it gets worse the further the value is from zero, since the missing 32 degrees is a fixed error rather than a proportional one.
Convert any temperature — or switch to Kelvin — instantly in the Unit Converter, which shows the exact formula for whichever direction you're converting.