Temperature conversion chart
Convert between Celsius, Fahrenheit, and Kelvin. Unlike most conversions, temperature uses formulas rather than simple factors, because the scales start at different zero points.
Conversion formulas
| Conversion | Formula |
|---|---|
| Celsius to Fahrenheit | F = C × 9/5 + 32 |
| Fahrenheit to Celsius | C = (F − 32) × 5/9 |
| Celsius to Kelvin | K = C + 273.15 |
| Kelvin to Celsius | C = K − 273.15 |
Common temperatures
| Description | °C | °F | K |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 20 | 68 | 293.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Water boils | 100 | 212 | 373.15 |
Temperature scales differ in both their zero point and their step size, so a single multiplier will not do. Celsius and Kelvin share the same step but start 273.15 apart, while Fahrenheit uses smaller degrees and a different zero. The scales cross at minus 40, where Celsius and Fahrenheit read the same.
Need unit conversions?
See the Metric Conversion Chart for length, mass, and volume.
Why temperature needs formulas
Most conversions multiply by a constant, but temperature scales have different starting points, so you must shift as well as scale. Going from Celsius to Fahrenheit, you scale by nine fifths to account for the smaller Fahrenheit degree, then add 32 because Fahrenheit puts freezing at 32 rather than 0. Kelvin keeps the Celsius degree size but moves zero down to absolute zero.
Kelvin and absolute zero
Kelvin is the scientific scale, starting at absolute zero, the coldest possible temperature where molecular motion stops. Because it shares the Celsius degree, converting is just adding or subtracting 273.15. Kelvin has no negative values and no degree symbol, and it is used throughout physics and chemistry.
FAQ
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. So 20°C is 20 × 1.8 + 32 = 68°F.
At what temperature are Celsius and Fahrenheit equal?
At minus 40 degrees. −40°C equals −40°F.
What is absolute zero?
The lowest possible temperature, 0 Kelvin, equal to −273.15°C or −459.67°F.