- Kelvin
- Also called K · SI base unit of temperature
- The SI unit of temperature, counted from absolute zero. Subtract 273.15 to get degrees Celsius: 300 K is 26.85 °C.
Kelvin to Celsius table
| Kelvins (K) | Degrees Celsius (°C) |
|---|---|
| 0 | -273.15 |
| 77 | -196.15 |
| 200 | -73.15 |
| 233.15 | -40 |
| 255.37 | -17.78 |
| 273.15 | 0 |
| 283.15 | 10 |
| Kelvins (K) | Degrees Celsius (°C) |
|---|---|
| 293.15 | 20 |
| 300 | 26.85 |
| 310.15 | 37 |
| 373.15 | 100 |
| 500 | 226.85 |
| 1,000 | 726.85 |
Reading kelvin values
Kelvin figures show up in science papers, astronomy and data sheets for electronics and cameras. Subtracting 273.15 turns them into something familiar: 293 K is about 20 °C, room temperature, and 5,772 K, the Sun's effective surface temperature, is about 5,499 °C.
Data sheets for chips and sensors often give operating limits in both units, such as 233.15 K to 358.15 K, which is −40 °C to 85 °C.
- 0 KAbsolute zero, −273.15 °C
- 77 KLiquid nitrogen boils, about −196 °C
- 273.15 KWater freezes, 0 °C
- 373.15 KWater boils at sea level, about 100 °C
Negative results and absolute zero
Any kelvin value below 273.15 gives a negative Celsius result, and that is normal: 250 K is −23.15 °C. A negative kelvin value, however, is not a real temperature, and the converter above will say so. The BIPM SI Brochure defines both scales and the 273.15 offset.
For US readers, celsius to fahrenheit is the next step, or go straight from Fahrenheit with fahrenheit to kelvin.
Cryogenics and space science often stay in kelvin because the numbers are small and positive: liquid helium boils near 4 K, about −269 °C. Converted to Celsius, such values turn into long negative figures that are harder to compare.
Color temperature is not heat
A 6500 K monitor setting or a 2700 K bulb describes the color of the light, not how hot the screen or bulb gets. Converting those values to Celsius gives a correct number with no practical meaning.
Kelvin to Celsius questions
What is 300 K in Celsius?
300 − 273.15 = 26.85 °C.
How do I convert kelvin to Fahrenheit?
Subtract 273.15 to get Celsius, then multiply by 1.8 and add 32. 300 K is 80.33 °F.
Why is the offset 273.15 and not 273?
The Celsius scale is defined from the kelvin with exactly that offset, which places 0 °C at the freezing point of water to within a tiny margin.
Is 0 K the same as 0 °C?
No. 0 K is absolute zero, −273.15 °C. 0 °C is 273.15 K.