Convert °C to °F and °F to °C with the exact formula and a quick mental trick, plus a table of common temperatures for weather, fever and cooking.
Weather apps, thermometers and recipes don't always use the same scale. Here are the two formulas you need, a mental shortcut, and the temperatures people look up most.
The formulas
- Celsius to Fahrenheit: °F = °C × 9/5 + 32 (or °C × 1.8 + 32)
- Fahrenheit to Celsius: °C = (°F − 32) × 5/9 (or (°F − 32) ÷ 1.8)
Worked examples
37 °C to °F: 37 × 1.8 = 66.6, then 66.6 + 32 = 98.6 °F (normal body temperature).
104 °F to °C: 104 − 32 = 72, then 72 ÷ 1.8 = 40 °C (a high fever, and a hot summer day in Pakistan).
A quick mental trick
For a rough °C to °F conversion: double it and add 30. 20 °C → 70 °F (exact: 68). For °F to °C: subtract 30 and halve it. 90 °F → 30 °C (exact: 32.2). It's close enough for weather, but use the exact formula for medicine and science.
Common temperatures
| What | °C | °F |
|---|---|---|
| Water freezes | 0 | 32 |
| Cool day | 15 | 59 |
| Room temperature | 22 | 71.6 |
| Normal body temperature | 37 | 98.6 |
| Fever | 38 | 100.4 |
| Very hot summer day | 45 | 113 |
| Water boils (sea level) | 100 | 212 |
| Baking a cake | 180 | 356 |
| Hot oven / pizza | 220 | 428 |
−40 is the one temperature that is the same on both scales.
What about Kelvin?
Kelvin is used in physics and chemistry: K = °C + 273.15. So 25 °C = 298.15 K. There's no degree sign with kelvin.
Convert instantly
The Temperature Converter converts between Celsius, Fahrenheit, Kelvin and Rankine and shows the formula it used. Need other units? Try the Length, Weight and Speed converters, or browse all Unit Converters.