How to Convert Kelvin to Celsius
The kelvin to Celsius formula, a worked example, a quick-reference chart, and why the offset is exactly 273.15.
Last updated: 2026-05-21
Converting kelvin to Celsius is one of the simplest conversions in science because the two scales share the same degree size. You only need to apply a single offset. The formula is:
°C = K − 273.15
Subtract 273.15 from any kelvin value and you have the equivalent Celsius temperature. There is no multiplication or scaling involved, because one kelvin is exactly equal in magnitude to one degree Celsius. The only thing that differs between the two scales is where they place their zero point.
Step by Step
Suppose a sensor reads 300 K and you want the temperature in Celsius. Work through it directly:
- Start with the kelvin value: 300 K.
- Subtract the offset: 300 − 273.15 = 26.85.
- Add the unit: 300 K = 26.85 °C.
That is the entire process. To check yourself with cleaner numbers, try 373.15 K: 373.15 − 273.15 = 100, so 373.15 K is exactly 100 °C, the boiling point of water at sea level. For instant results across any value, use the temperature converter.
Kelvin to Celsius Chart
These reference points cover the values you are most likely to encounter:
| Kelvin (K) | Celsius (°C) | Notable point |
|---|---|---|
| 0 K | −273.15 °C | Absolute zero |
| 255.37 K | −17.78 °C | 0 °F |
| 273.15 K | 0 °C | Freezing point of water |
| 293.15 K | 20 °C | Room temperature |
| 300 K | 26.85 °C | Warm day |
| 310.15 K | 37 °C | Human body temperature |
| 373.15 K | 100 °C | Boiling point of water |
Why 273.15?
The kelvin scale begins at absolute zero — the theoretical point where particles carry the minimum possible thermal energy and classical motion stops. The Celsius scale, by contrast, anchors its zero to the freezing point of water. Those two reference points are separated by exactly 273.15 degrees, which is why the offset is a fixed constant rather than a ratio.
Because both scales use the same degree size, the gap never changes as the temperature rises or falls. A 10-kelvin increase is always a 10-degree-Celsius increase. This is also why temperature differences and rates — in physics, chemistry, and engineering — can be quoted in kelvin or Celsius interchangeably, while absolute temperatures must always carry the 273.15 correction.
Once you know the offset, the conversion takes seconds. To convert in the other direction, add 273.15 to your Celsius value. For quick, precise results in either direction, open the temperature converter.