Temperature Converter
Celsius, Fahrenheit, Kelvin, and Rankine, with the offset handled properly.
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Decimals and fractions both work — 1.5 or 1 1/2.
20 °C = 68 °F
20 °C in every other unit
- Fahrenheit (°F)68
- Kelvin (K)
Written without a degree sign — "300 K", not "300 °K".
293.15 - Rankine (°R)
Absolute zero with Fahrenheit-sized degrees. Used in some US engineering.
527.67
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How it works
To convert a temperature, enter it above and pick its scale — Celsius to Fahrenheit multiplies by 9/5 and then adds 32, because the two scales have different zero points as well as different degree sizes, and the converter applies both steps in your browser.
Temperature is the one conversion on this site that is not a multiplication. Every other unit is a pure scale factor — a metre is a fixed number of feet at any size — but Celsius and Fahrenheit disagree about both how large a degree is and where zero sits. So the conversion is affine: multiply by the ratio of degree sizes, then shift by the offset between the zeros. °F = °C × 9/5 + 32, and back the other way °C = (°F − 32) × 5/9.
Forgetting the offset is the classic error, and it is silent: 20 °C becomes 36 °F instead of 68 °F, which is a plausible-looking temperature rather than an obvious mistake. Internally this converter routes every scale through kelvin, where zero is the physical zero, so the offset is applied once in a single place rather than in four hand-written formulas that can each be wrong separately.
That base is also what lets the tool refuse impossible input. Below absolute zero — −273.15 °C, −459.67 °F, 0 K — there is no temperature to convert, but the arithmetic does not care: a mistyped −300 °C converts happily to −508 °F, which looks like an answer. Anything below the physical floor is rejected with an explanation instead.
One caveat the converter cannot express for you: this converts temperatures, not temperature *differences*. A rise of 10 °C is a rise of 18 °F, not 50 °F, because a difference has no zero point to shift. Multiply differences by 9/5 alone and leave the +32 out.
Celsius to Fahrenheit
Multiply by 9/5 and add 32. The two scales cross at −40, which is the same temperature in both — a useful sanity check on any conversion.
| Celsius | Fahrenheit |
|---|---|
| -40 °C | -40 °F |
| -10 °C | 14 °F |
| 0 °C | 32 °F |
| 10 °C | 50 °F |
| 20 °C | 68 °F |
| 25 °C | 77 °F |
| 30 °C | 86 °F |
| 37 °C | 98.6 °F |
| 100 °C | 212 °F |
Oven temperatures
Recipe ovens are the most common reason to convert, and oven dials are marked in round numbers rather than exact conversions — a "180 °C" recipe is a "350 °F" recipe even though the exact conversion is 356 °F. Gas mark 4 is the same setting again.
| Celsius | Fahrenheit |
|---|---|
| 120 °C | 248 °F |
| 140 °C | 284 °F |
| 150 °C | 302 °F |
| 160 °C | 320 °F |
| 180 °C | 356 °F |
| 190 °C | 374 °F |
| 200 °C | 392 °F |
| 220 °C | 428 °F |
| 230 °C | 446 °F |
| 240 °C | 464 °F |
Fahrenheit to Celsius
Subtract 32 first, then multiply by 5/9. Doing the two steps in the wrong order is the second most common temperature error after dropping the offset entirely.
| Fahrenheit | Celsius |
|---|---|
| 0 °F | -17.7778 °C |
| 32 °F | 0 °C |
| 50 °F | 10 °C |
| 68 °F | 20 °C |
| 72 °F | 22.2222 °C |
| 90 °F | 32.2222 °C |
| 98.6 °F | 37 °C |
| 100 °F | 37.7778 °C |
| 212 °F | 100 °C |
FAQ
What is the formula to convert Celsius to Fahrenheit?
°F = °C × 9/5 + 32. To go the other way, °C = (°F − 32) × 5/9. The multiplication and the offset are both required — a degree Fahrenheit is 5/9 the size of a degree Celsius and the scales start in different places.
What temperature is the same in Celsius and Fahrenheit?
−40. It is the single point where the two scales cross, which makes it a quick way to check that a conversion formula has been written down correctly.
What is 180 °C in Fahrenheit?
356 °F exactly, but every oven dial and recipe rounds it to 350 °F. Ovens are not accurate to six degrees, so the rounding is standard rather than sloppy.
Why does Kelvin have no degree sign?
Because it is an absolute scale rather than a degree scale. Since 1967 the unit is written "300 K", not "300 °K". Its zero is absolute zero, so kelvin values are never negative.
How do I convert a temperature difference?
Multiply by 9/5 or 5/9 and leave the offset out entirely. A 10 °C rise is an 18 °F rise. The +32 exists to align two different zero points, and a difference does not have one.