Kelvin to Celsius (K to °C)
The Celsius scale is the kelvin scale shifted by exactly 273.15 (SI Brochure, BIPM; NIST SP 811 §4.2.1.1), and one kelvin is the same size as one degree Celsius. So subtract 273.15: 300 K is 26.85 °C, and 0 K — absolute zero — is −273.15 °C.
Formula
°C = K − 273.15
Example: 100 kelvin = -173.15 degrees Celsius.
Kelvin to Celsius chart
| kelvin | degrees Celsius |
|---|---|
| 0 | -273.15 |
| 4.2 | -268.95 |
| 77 | -196.15 |
| 100 | -173.15 |
| 200 | -73.15 |
| 250 | -23.15 |
| 273.15 | 0 |
| 283.15 | 10 |
| 293.15 | 20 |
| 298.15 | 25 |
| 300 | 26.85 |
| 310.15 | 37 |
| 373.15 | 100 |
| 500 | 226.85 |
| 1,000 | 726.85 |
| 5,778 | 5,504.85 |
Good to know
Same step size: because a change of 1 K equals a change of 1 °C, temperature differences need no conversion at all. A reaction that warms by 15 K warmed by 15 °C. Only absolute readings need the 273.15 offset.
Science reference points: liquid helium boils at 4.2 K (−268.95 °C), liquid nitrogen at 77 K (−196.15 °C), water freezes at 273.15 K and boils at 373.15 K at standard pressure, human body temperature is about 310.15 K (37 °C) and the Sun's surface is about 5,778 K (5,504.85 °C).
Kelvin, not degrees kelvin: since 1967 the unit is written 'kelvin' with the symbol K and no degree sign. Kelvin values are never negative. Light bulb 'color temperature' (2,700 K warm white, 5,000 K daylight) uses the same unit to describe the color of light, not how hot the bulb gets.
Frequently asked questions
How do you convert kelvin to Celsius?
Subtract 273.15. For example, 350 K − 273.15 = 76.85 °C.
What is 0 K in Celsius?
0 K is −273.15 °C — absolute zero, the lowest possible temperature.
What is 300 K in Celsius?
300 K is 26.85 °C, a warm room temperature.
Is 273 or 273.15 correct?
273.15 is exact. 273 is a common classroom rounding and is off by 0.15 °C.