Celsius is the temperature scale of weather forecasts, recipes and science almost everywhere; Fahrenheit is still the everyday scale in the United States. Because the two scales have different zero points, you can’t convert with a single multiplication — this converter applies the full formula, shows each step, and refuses any value below absolute zero.
How to use the Celsius to Fahrenheit converter
- Enter a temperature in Temperature in Celsius (°C). Negative values are fine.
- Read the answer in °F. Below it are the same temperature in kelvin and Rankine, and what your number means if it is a temperature change rather than a reading.
- Scroll down for the worked steps and a chart from −40 °C to 260 °C with reference points such as freezers, fevers and oven settings.
The Celsius to Fahrenheit formula
The 9/5 (or 1.8) accounts for the different size of the degrees: water freezes at 0 °C and 32 °F and boils at 100 °C and 212 °F, so 100 Celsius degrees span the same range as 180 Fahrenheit degrees. The +32 shifts the starting point, because Fahrenheit’s zero sits 32 degrees below the freezing point of water.
Worked example: a recipe’s 180 °C oven
Step 1. Multiply by 1.8: 180 × 1.8 = 324.
Step 2. Add 32: 324 + 32 = 356 °F.
In practice. Set a US oven to 350 °F. Oven thermostats swing by more than 6 °F as they cycle.
For a weather example: a forecast of 22 °C is 22 × 1.8 + 32 = 71.6 °F — a mild, comfortable day.
Oven temperatures: Celsius, Fahrenheit and gas mark
British and European recipes often list a gas mark or a fan-oven setting alongside Celsius. Cookbooks round the Fahrenheit values to the nearest 25 degrees, so they don’t match the exact formula — use the rounded column when setting a US oven dial.
| Gas mark | °C (conventional) | °F as printed in recipes | Exact °F | °C (fan oven) |
|---|---|---|---|---|
| 1 | 140 | 275 | 284 | 120 |
| 2 | 150 | 300 | 302 | 130 |
| 3 | 170 | 325 | 338 | 150 |
| 4 | 180 | 350 | 356 | 160 |
| 5 | 190 | 375 | 374 | 170 |
| 6 | 200 | 400 | 392 | 180 |
| 7 | 220 | 425 | 428 | 200 |
| 8 | 230 | 450 | 446 | 210 |
| 9 | 240 | 475 | 464 | 220 |
Fan (convection) ovens cook faster, so recipes typically reduce the temperature by about 20 °C. If your US oven has a convection setting, a common rule is to drop the Fahrenheit temperature by 25 °F.
The “double it and add 30” shortcut
For weather this mental trick is handy, but it drifts the further you get from about 10 °C:
| °C | Shortcut (×2 + 30) | Exact °F | Error |
|---|---|---|---|
| 0 | 30 | 32 | −2 |
| 10 | 50 | 50 | 0 |
| 20 | 70 | 68 | +2 |
| 30 | 90 | 86 | +4 |
| 37 | 104 | 98.6 | +5.4 |
| 180 | 390 | 356 | +34 |
It’s fine for deciding whether to bring a jacket, useless for body temperature or baking. For those, use the exact formula — or this converter.
Temperatures vs temperature differences
If a recipe says “raise the heat by 10 °C” or a forecast says “5 °C warmer than yesterday”, that is a difference, and only the 1.8 factor applies: 10 °C warmer is 18 °F warmer, not 50 °F. The converter shows this interpretation in the As a temperature change row. To convert the other way, use Fahrenheit to Celsius, or see all four scales at once in the temperature converter.
Frequently asked questions
What is the formula to convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 (that is, 1.8) and then add 32. For 25 °C: 25 × 1.8 = 45, and 45 + 32 = 77 °F.
What is 180 °C in Fahrenheit?
180 °C is exactly 356 °F. Recipes translated for US ovens usually round this to 350 °F, a difference home ovens barely notice.
At what temperature are Celsius and Fahrenheit equal?
At −40. Setting C = 1.8C + 32 gives C = −40, so −40 °C and −40 °F describe the same temperature.
Is there an easy way to estimate °C to °F?
Double the Celsius figure and add 30. It is accurate within about 2 °F between 0 °C and 20 °C, which covers most weather, but it overshoots badly for hot values such as oven temperatures.
Why does a 10 °C rise equal an 18 °F rise?
A Fahrenheit degree is smaller than a Celsius degree; 180 Fahrenheit degrees fit between freezing and boiling, against 100 Celsius degrees. So temperature changes convert by 1.8 alone, without the +32 offset.