Temperature Converter
Celsius, Fahrenheit, Kelvin, and Rankine, converted correctly.
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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 to use it
Enter a temperature and pick its scale to convert it. Celsius to Fahrenheit: multiply by 9/5, then add 32. Fahrenheit to Celsius: subtract 32, then multiply by 5/9.
Type a temperature and pick its scale — the answer appears in Celsius, Fahrenheit, Kelvin, and Rankine at once.
The formula: °F = °C × 9/5 + 32. Going back: °C = (°F − 32) × 5/9. The most common mistake is forgetting the “+ 32”, which turns 20 °C into 36 °F instead of the correct 68 °F.
Fun fact: −40 is the same in both Celsius and Fahrenheit. Handy for checking your maths.
Converting a change in temperature, like “it rose by 10 °C”? Leave out the 32: a 10 °C rise is an 18 °F rise.
Celsius to Fahrenheit
Multiply by 9/5 and add 32. The two scales meet at −40, which is the same in both.
| 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
Ovens are the most common reason to convert. Oven dials use round numbers, so a 180 °C recipe means 350 °F (exactly, it’s 356 °F). That’s also gas mark 4.
| 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 it the other way round gives the wrong answer.
| 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 for Celsius to Fahrenheit?
°F = °C × 9/5 + 32. For the reverse, °C = (°F − 32) × 5/9.
Which temperature is the same in Celsius and Fahrenheit?
−40.
What is 180 °C in Fahrenheit?
Exactly 356 °F, but recipes and ovens round it to 350 °F.
Why doesn’t Kelvin have a degree sign?
It’s an absolute scale that starts at absolute zero, so it’s written “300 K”, not “300 °K”.
How do I convert a change in temperature?
Multiply by 9/5 and leave out the 32. A 10 °C rise is an 18 °F rise.
How it worksFor the curious
Temperature conversion is affine rather than a pure scale factor: Celsius and Fahrenheit differ in both degree size and zero point. Every scale is routed through kelvin, where zero is physical zero, so the offset is applied in one place rather than in separate hand-written formulas.
That base also lets the tool reject impossible input. Below absolute zero — −273.15 °C, −459.67 °F, 0 K — there is no temperature; a mistyped −300 °C would otherwise convert to a plausible-looking −508 °F.
Kelvin is an absolute scale, written “300 K” without a degree sign since 1967. Temperature differences scale by 9/5 alone, because a difference has no zero point to shift.