How to Convert Celsius to Kelvin
Kelvin is the SI (International System of Units) base unit for temperature, used primarily in scientific contexts. Unlike Celsius and Fahrenheit, Kelvin is an absolute temperature scale—it starts at absolute zero, the coldest possible temperature where all molecular motion stops.
Converting Celsius to Kelvin is one of the simplest temperature conversions because the two scales use the same size degree; Kelvin is simply shifted by 273.15.
The Conversion Formula
K = °C + 273.15
Going the other direction:
°C = K − 273.15
Step-by-Step Examples
Example 1: Water boils at 100°C. What is that in Kelvin?
- 100 + 273.15 = 373.15 K
Example 2: Absolute zero is 0 K. What is that in Celsius?
- 0 − 273.15 = −273.15°C
Reference Table
| Celsius | Kelvin | Context |
|---|---|---|
| −273.15°C | 0 K | Absolute zero |
| −196°C | 77.15 K | Liquid nitrogen boils |
| 0°C | 273.15 K | Water freezes |
| 20°C | 293.15 K | Room temperature |
| 37°C | 310.15 K | Body temperature |
| 100°C | 373.15 K | Water boils |
Why Scientists Use Kelvin
Kelvin is essential in thermodynamics because many physical laws (like the Ideal Gas Law: PV = nRT) require absolute temperature. Using Celsius in these equations would give incorrect results because 0°C is not the absence of heat—it's just the freezing point of water.
Use our Celsius-to-Kelvin calculator for quick scientific temperature conversions.