Kelvin to Celsius formula
The SI unit. 0 K is absolute zero; a kelvin is the same size as a Celsius degree. Written without “degree”.
Kelvin to Celsius chart
| Kelvins (K) | Degrees Celsius (°C) |
|---|---|
| 0 | -273.15 |
| 4 | -269.15 |
| 77 | -196.15 |
| 173.15 | -100 |
| 233.15 | -40 |
| 253.15 | -20 |
| 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 |
| 2,700 | 2,426.85 |
| 4,000 | 3,726.85 |
| 5,000 | 4,726.85 |
| 6,500 | 6,226.85 |
Values are rounded to 4 decimal places. The converter above shows more precision.
Worked examples
Room temperature in a physics problem (300 K)
°C = 300 − 273.15 = 26.85
300 kelvins = 26.85 degrees Celsius. That is 26.85 °C, a warm room. Textbooks pick 300 K because it is a round number close to everyday conditions.
Liquid nitrogen at about 77 K
°C = 77 − 273.15 = -196.15
77 kelvins = -196.15 degrees Celsius. Roughly −196 °C. Liquid nitrogen boils near this temperature, which is why it is used to freeze samples and in science demos.
Converting kelvins to degrees Celsius in real life
Kelvin is the SI unit of temperature, so it is the one used in physics and chemistry. Gas law problems, thermodynamics and astronomy data are usually given in kelvin. Convert back to Celsius when you want a number that means something in daily life.
A few things trip students up:
- Kelvin is written without a degree sign: 300 K, not 300 °K.
- Many textbooks round to 273. Use 273.15 unless your course says otherwise.
- A temperature difference is the same in both: a rise of 10 K is a rise of 10 °C.
Light bulbs are also rated in kelvin. A “2700 K warm white” bulb is not that hot; the number describes the colour of its light, matching how a very hot object would glow at that temperature. Daylight-style bulbs are around 5000 to 6500 K.