The formulas
°C = (°F − 32) × 5/9
K = °C + 273.15
For example, normal body temperature of 37 °C is 37 × 1.8 + 32 = 98.6 °F, and 20 °C (a comfortable room) is 68 °F.
Reference table
| What | °C | °F |
|---|---|---|
| Water freezes | 0 | 32 |
| Cool room | 20 | 68 |
| Normal body temperature | 37 | 98.6 |
| Hot day | 35 | 95 |
| Water boils (sea level) | 100 | 212 |
| Same in both scales | −40 | −40 |
Oven temperatures
Recipes often use one scale while your oven uses the other. Many ovens are set in steps, so use the nearest setting:
| °F | °C (exact) | Common setting |
|---|---|---|
| 325 | 163 | 160 or 165 |
| 350 | 177 | 175 or 180 |
| 375 | 191 | 190 |
| 400 | 204 | 200 |
| 425 | 218 | 220 |
| 450 | 232 | 230 |
If your oven runs hot or cold, or is fan-assisted, you may need to adjust further. Many recipes suggest reducing the temperature by about 20 °C (25 °F) for a fan oven.
A quick mental shortcut
To turn Celsius into a rough Fahrenheit figure, double it and add 30. So 25 °C is about 80 °F (the exact answer is 77 °F). It is close enough for weather, but not for cooking or science.
Where each scale is used
Celsius is used in most countries and in science alongside Kelvin. Fahrenheit is used in everyday life in the United States and a few other places. Kelvin starts at absolute zero, the lowest possible temperature, which is −273.15 °C, so it never has negative values.