Celsius vs Fahrenheit
Side-by-side comparison, when-to-use-each guide, and instant conversion. Reviewed for 2026.
Most of the world. UK weather and recipes. Scientific work (alongside Kelvin).
United States, Bahamas, Belize, Cayman Islands, Palau. Some older UK ovens still show Fahrenheit alongside Celsius.
| Aspect | Celsius | Fahrenheit |
|---|---|---|
| Freezing point of water | 0°C | 32°F |
| Boiling point of water | 100°C | 212°F |
| Normal body temperature | 37°C | 98.6°F |
| Comfortable room | 20-22°C | 68-72°F |
| Origin | Anders Celsius, 1742 | Daniel Fahrenheit, 1724 |
Frequently asked
What's the easy mental conversion?
For °C to °F: double the Celsius, subtract 10%, add 32. (E.g. 20°C × 2 = 40, − 4 = 36, + 32 = 68°F.) For °F to °C: subtract 30, halve. Not exact but within 3°C for everyday weather.
Why is normal body temp 98.6°F?
It's a rounded conversion of 37°C. The 'official' 98.6°F is misleadingly precise — actual normal body temp varies by 1°F throughout the day, by individual, and by measurement method.
Frequently asked questions
What's the easy mental conversion?
For °C to °F: double the Celsius, subtract 10%, add 32. (E.g. 20°C × 2 = 40, − 4 = 36, + 32 = 68°F.) For °F to °C: subtract 30, halve. Not exact but within 3°C for everyday weather.
Why is normal body temp 98.6°F?
It's a rounded conversion of 37°C. The 'official' 98.6°F is misleadingly precise — actual normal body temp varies by 1°F throughout the day, by individual, and by measurement method.