celsius to fahrenheit
Nine fifths, plus thirty-two. Both fields work.
The short answer
Multiply the Celsius figure by nine fifths and add 32: 20 °C is 68 °F. Body temperature, 37 °C, is 98.6 °F, and the two scales meet at −40.
Temperature is the one everyday conversion with an offset in it, which is why the mental shortcuts people use get closer to wrong the further you go from room temperature.
The formula
°F = °C × 9 ÷ 5 + 32
Worked examples
- 20 °C
- 68 °F
- 37 °C
- 98.6 °F
- 180 °C
- 356 °F
Reference table
| Celsius | Fahrenheit | What it is |
|---|---|---|
| -40 °C | -40 °F | Where the two scales meet |
| 0 °C | 32 °F | Water freezes |
| 10 °C | 50 °F | A cold day |
| 20 °C | 68 °F | Room temperature |
| 30 °C | 86 °F | A hot day |
| 37 °C | 98.6 °F | Body temperature |
| 40 °C | 104 °F | A fever, or a heatwave |
| 100 °C | 212 °F | Water boils |
| 180 °C | 356 °F | A moderate oven |
| 220 °C | 428 °F | A hot oven |
How to use it
- 01Type either scaleCelsius on the left, Fahrenheit on the right. Both fields are live and each rewrites the other.
- 02Read the line underneathIt restates the conversion in words, so you can see which direction the tool understood.
Also searched for
Searches that land here include celsius to fahrenheit, c to f, fahrenheit to celsius, 37 celsius in fahrenheit and convert centigrade to fahrenheit.
Two scales, one straight line
Where the numbers come from
Fahrenheit put zero at the coldest temperature he could reproduce with a salt and ice mixture and set body temperature near 96. Celsius anchored his scale to water: zero at freezing, a hundred at boiling, at sea level. Two anchors, chosen for different reasons, which is why converting between them needs both a multiplication and an addition rather than just a factor.
The offset is what makes it awkward
Every other everyday conversion on this site is one multiplication, so a ratio holds all the way up and down the scale. Temperature is not: 20 °C is not twice 10 °C in Fahrenheit terms, and no shortcut that skips the offset stays accurate across the range. That is also why a temperature difference converts differently from a temperature. A rise of 10 °C is a rise of 18 °F, with no 32 involved.
Which scale, where
Fahrenheit is in everyday use in the United States and a handful of territories. Everywhere else uses Celsius for weather, cooking and medicine, while science uses kelvin for anything absolute. Ovens are the awkward case: recipes travel, and a moderate oven is 180 °C or 356 °F, usually written as 350.
Questions people ask
What is 37 °C in Fahrenheit?
98.6 °F, the figure usually quoted as normal body temperature. It is worth knowing that the 98.6 is an artefact of converting a rounded 37 °C: the original nineteenth-century measurements averaged nearer 36.8 °C, and normal varies by person, by site of measurement and through the day.
Does the double it and add 30 trick work?
Roughly, and only near room temperature. Doubling and adding 30 gives 70 °F for 20 °C where the answer is 68 °F, an error of two degrees. By 100 °C the same trick is out by 18 degrees, because it uses two instead of nine fifths.
Why do the two scales meet at −40?
Because the conversion is a straight line with a slope of 1.8 and an offset of 32, and −40 is the one point where those cancel out. It is the only temperature that reads the same on both scales, which is why weather reports in Canada can print it without saying which one they mean.