Kelvin to Celsius formula
°C = K − 273.15
Example: 298.15K − 273.15 = 25°C
About the Kelvin scale
The kelvin is the SI unit of thermodynamic temperature. Its zero point, 0 K, is absolute zero, the lowest possible temperature on the standard thermodynamic scale. Unlike Celsius and Fahrenheit, kelvin is written without a degree symbol: 300 K, not 300°K.
The kelvin and Celsius scales have the same size temperature increment, but their zero points are offset by 273.15 degrees. This makes Kelvin especially useful for scientific calculations in physics, chemistry, and astronomy.
About the Celsius scale
The Celsius scale is widely used for everyday temperatures and scientific measurements. Under standard atmospheric pressure, water freezes at 0°C and boils at 100°C. The Celsius and Kelvin scales use the same size temperature increment, so converting between them only requires adding or subtracting 273.15.
Reference table
| Kelvin | Celsius |
|---|---|
| 0K | −273.15°C (absolute zero) |
| 273.15K | 0°C (freezing) |
| 293.15K | 20°C (room temperature) |
| 300K | 26.85°C |
| 310.15K | 37°C (approximate body temperature) |
| 373.15K | 100°C (boiling) |
Frequently asked questions
How do I convert Kelvin to Celsius in my head?
Subtract 273.15 for an exact conversion. For a quick estimate, subtract 273 instead. For example, 300 K is about 27°C.
What is 0 Kelvin in Celsius?
0 K, absolute zero, equals −273.15°C. For ordinary temperature conversion, Kelvin values are entered at 0 K or above.
Why does Kelvin start at a different zero than Celsius?
The Celsius scale uses 0°C and 100°C as important reference points for water under standard atmospheric pressure. The Kelvin scale instead sets its zero point at absolute zero. Because one kelvin is the same size as one degree Celsius, the two scales differ by a constant offset of 273.15.
Need the reverse direction? See Celsius to Kelvin.