Temperature converter
Type into any box. Celsius, Fahrenheit, Kelvin and Rankine update together, and the thermometer follows. Drag the thermometer to go the other way.
Pick a conversion
- °C → °FCelsius to Fahrenheit
- °C → KCelsius to Kelvin
- °C → °RCelsius to Rankine
- °F → °CFahrenheit to Celsius
- °F → KFahrenheit to Kelvin
- °F → °RFahrenheit to Rankine
- K → °CKelvin to Celsius
- K → °FKelvin to Fahrenheit
- K → °RKelvin to Rankine
- °R → °CRankine to Celsius
- °R → °FRankine to Fahrenheit
- °R → KRankine to Kelvin
Four scales, two differences
Every temperature scale answers two questions differently: how big is one degree, and where is zero. Celsius and Kelvin share a degree size and differ only in their zero (Kelvin starts at absolute zero, 273.15 below 0 °C). Fahrenheit and Rankine share a smaller degree, 5/9 of a Celsius degree, and again differ only in zero: Rankine starts at absolute zero too, 459.67 below 0 °F.
So every conversion is at most a stretch (×9/5 or ×5/9) and a shift (add or remove 32, 273.15 or 459.67). The Celsius to Fahrenheit page lets you step through the stretch and the shift one at a time.
Landmarks worth remembering
| Landmark | °C | °F | K |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Celsius equals Fahrenheit | −40 | −40 | 233.15 |
| Water freezes | 0 | 32 | 273.15 |
| Comfortable room | 20 | 68 | 293.15 |
| Typical body temperature | 37 | 98.6 | 310.15 |
| Water boils (sea level) | 100 | 212 | 373.15 |
| Moderate oven, gas mark 4 | 180 | 350 | 453.15 |
Guides
- Oven temperatures°C, fan, °F and gas mark side by side, plus a recipe rewriter.
- Body temperatureTypical ranges and the fever threshold in °C and °F, with sources.
- Conversion chartPrintable Celsius to Fahrenheit chart from −50 to 300 °C.
- All 12 formulasEvery pair between C, F, K and R, with worked steps.
- Celsius vs FahrenheitWhy the scales differ and why the mental shortcut fails in the oven.
- Absolute zeroWhere Kelvin and Rankine start, and what 0 K means.
- The Rankine scaleAbsolute zero with Fahrenheit-sized degrees, explained with a chart.
- Room temperatureComfortable indoor, weather and fridge temperatures in both scales.
- Ask a temperature questionPlain-English answers to anything about temperature and its units.
Questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 (1.8) and add 32. 20 °C × 1.8 = 36, plus 32 = 68 °F.
How do I convert Fahrenheit to Celsius?
Subtract 32 and multiply by 5/9. 350 °F − 32 = 318, × 5/9 = 176.7 °C.
How do I convert Celsius to Kelvin?
Add 273.15. 25 °C is 298.15 K. Kelvin is written without a degree sign.
Does the converter work offline?
Yes. All the maths runs in your browser, so once the page has loaded it keeps working without a connection. Only the optional AI tools need to be online.
Where is my conversion history stored?
Only in your browser (localStorage). Nothing is sent to us, and the Clear history button removes it.