The Celsius to Fahrenheit formula
Converting Celsius to Fahrenheit takes one short formula: °F = °C × 9/5 + 32. Multiply the Celsius temperature by nine fifths (that is, by 1.8), then add 32. The two scales put their zero points in different places, which is why you need the +32 shift — temperature is the one conversion you can never do with multiplication alone.
Worked example: take a mild 20 °C day. Multiply by 9/5 to get 36, add 32, and you have 68 °F. Going the other way, the reverse formula is °C = (°F − 32) × 5/9: subtract 32 first, then multiply by five ninths.
For a quick estimate in your head, use the shortcut "double it and add 30": 20 °C doubles to 40, plus 30 gives 70 °F — close to the true 68. It's only approximate, though, and drifts by a few degrees the further you move from about 10 °C (where it happens to be exact). Use it for weather chat, not for cooking or science.
Celsius to Fahrenheit chart
Exact values from the formula — handy anchors include −40° (the one temperature where both scales agree), 0 °C = 32 °F (freezing), 37 °C = 98.6 °F (body temperature) and 100 °C = 212 °F (boiling).
| Celsius (°C) | Fahrenheit (°F) | Good to know |
|---|---|---|
| −40 °C | −40 °F | The scales cross — same number on both |
| −20 °C | −4 °F | Deep-freezer territory |
| −10 °C | 14 °F | A hard frost |
| 0 °C | 32 °F | Water freezes |
| 5 °C | 41 °F | Fridge-cold morning |
| 10 °C | 50 °F | Cool day |
| 15 °C | 59 °F | Mild |
| 20 °C | 68 °F | Comfortable room temperature |
| 25 °C | 77 °F | Warm day |
| 30 °C | 86 °F | Hot day |
| 37 °C | 98.6 °F | Human body temperature |
| 40 °C | 104 °F | Heatwave |
| 50 °C | 122 °F | Hottest recorded air temperatures |
| 100 °C | 212 °F | Water boils (at sea level) |
| 180 °C | 356 °F | Moderate oven |
| 200 °C | 392 °F | Hot oven |
| 220 °C | 428 °F | Very hot oven |
Oven temperatures
Recipes round oven temperatures to friendly numbers, so the Fahrenheit you see in an American cookbook rarely matches the exact conversion. 180 °C is really 356 °F, but recipes say 350 °F — and at oven precision that difference doesn't matter. The table below gives both the exact conversion and the figure recipes commonly use, plus the UK gas mark.
| Oven description | °C | Exact °F | Common in recipes | Gas mark |
|---|---|---|---|---|
| Very slow | 120 °C | 248 °F | 250 °F | ½ |
| Slow | 150 °C | 302 °F | 300 °F | 2 |
| Moderate | 180 °C | 356 °F | 350 °F | 4 |
| Moderately hot | 190 °C | 374 °F | 375 °F | 5 |
| Hot | 200 °C | 392 °F | 400 °F | 6 |
| Very hot | 230 °C | 446 °F | 450 °F | 8 |
If you're using a fan-forced (convection) oven, the usual advice is to set it about 20 °C lower than the conventional temperature a recipe gives — check your oven's manual.
Need more than temperature? The universal converter on our home page handles length, weight, volume, area, speed, pressure and more in one tool — and pairs nicely with the cups to grams converter when an American recipe throws both Fahrenheit ovens and cup measurements at you. For quick answers, try the FAQ.