Kelvin to Celsius formula
°C = K − 273.15 Example: 298.15K − 273.15 = 25°C About the Kelvin scale
The Kelvin scale is an absolute thermodynamic temperature scale used universally across physics, astronomy, and chemistry. Created by physicist William Thomson (Lord Kelvin) in 1848, it eliminates negative numbers entirely by setting its starting point (0K) at absolute zero. Because the increments match the scale of Celsius perfectly, it provides a highly predictable framework for scientific calculations.
About the Celsius scale
The Celsius scale (originally known as the centigrade scale) is the dominant standard for monitoring daily temperatures in almost every country. Established by Swedish astronomer Anders Celsius in 1742, it scales smoothly alongside the states of water: freezing at 0°C and boiling at 100°C. It serves as a highly practical metric for human life and climate monitoring.
Reference table
| Kelvin | Celsius |
|---|---|
| 0K | −273.15°C (absolute zero) |
| 273.15K | 0°C (freezing) |
| 293.15K | 20°C (room temperature) |
| 310.15K | 37°C (body temperature) |
| 373.15K | 100°C (boiling) |
Frequently asked questions
How do I convert Kelvin to Celsius in my head?
Subtract 273 as a quick estimate, or 273.15 for the precise figure. 300K is roughly 27°C — close to a warm room temperature.
What is 0 Kelvin in Celsius?
0 Kelvin, absolute zero, equals −273.15°C. It is the coldest temperature theoretically possible, and this calculator enforces it as the lower bound for Kelvin input.
Why does Kelvin start at a different zero than Celsius?
Celsius was defined around water's freezing and boiling points, which was practical for everyday and early scientific use. Kelvin was defined later, in the 1800s, to start at true thermodynamic zero — the point where molecular motion stops — which turned out to sit exactly 273.15 degrees below Celsius's zero.
Need the reverse direction? See Celsius to Kelvin.