Celsius ↔ Kelvin Converter
Conversion Table
| Celsius (°C) | Kelvin (K) | Note |
|---|---|---|
| -273.15 | 0 | Absolute Zero |
| -200 | 73.15 | Liquid nitrogen range |
| -100 | 173.15 | — |
| 0 | 273.15 | Water Freezing Point |
| 20 | 293.15 | Room Temperature |
| 37 | 310.15 | Body Temperature |
| 100 | 373.15 | Water Boiling Point |
| 500 | 773.15 | — |
| 1000 | 1273.15 | — |
How to Convert Celsius to Kelvin
The Celsius to Kelvin conversion is one of the simplest in science, yet it underpins virtually all thermodynamic calculations. Our free converter lets you convert °C to K instantly in both directions, displaying the formula so you can understand every step.
The Celsius to Kelvin Formula
The formula is beautifully simple:
K = °C + 273.15
To go from Kelvin back to Celsius:
°C = K − 273.15
For example, 25°C + 273.15 = 298.15 K, which is a common reference temperature in chemistry.
Understanding the Kelvin Scale
The Kelvin scale is the SI base unit of thermodynamic temperature. It was named after the British physicist Lord Kelvin (William Thomson), who proposed an absolute temperature scale in 1848. Unlike Celsius or Fahrenheit, the Kelvin scale has no negative values because it starts at absolute zero — the point at which all molecular thermal motion theoretically ceases.
Absolute zero is 0 K, which equals −273.15°C. It is physically impossible to go below this temperature. The International Bureau of Weights and Measures (BIPM) formally defines the Kelvin based on the Boltzmann constant.
Scientific Uses of Kelvin
Scientists and engineers prefer Kelvin in a wide range of disciplines. In thermodynamics and the ideal gas law (PV = nRT), temperature must be expressed in Kelvin. In astrophysics, stellar temperatures reach thousands or millions of Kelvin. In cryogenics, researchers work with temperatures just fractions of a degree above absolute zero. Even everyday chemistry labs often convert room temperature (20°C = 293.15 K) for calculations.
Key Reference Temperatures in Kelvin
- Absolute Zero: 0 K = −273.15°C — lowest possible temperature.
- Liquid Nitrogen: ~77 K = −196°C — used for cryogenic storage.
- Water Freezing: 273.15 K = 0°C
- Room Temperature: ~293–298 K = 20–25°C
- Water Boiling: 373.15 K = 100°C
- Surface of the Sun: ~5,778 K