Celsius to Kelvin Converter
Two-way converter: change Celsius to Kelvin or Kelvin to Celsius in one step.
Type a value in either field for an instant conversion
About converting Celsius and Kelvin
The Celsius scale is used in everyday weather and cooking, while Kelvin is the SI base unit of thermodynamic temperature used in science. The scales have the same step size — a change of 1 °C equals a change of 1 K — but their zero points differ by 273.15.
To convert Celsius to Kelvin, use the formula: K = °C + 273.15. The reverse formula handles the other direction automatically — type into either field.
Every calculation runs locally in your browser and updates instantly — nothing is uploaded, and the result appears the moment you type.
Why use this converter
Works both ways
Convert °C to K or K to °C by typing in either field.
Exact formula
Uses the standard temperature conversion formula with no shortcuts.
No install
Runs in any browser on phone or desktop, with no sign-up required.
Frequently asked questions
How do I convert Celsius to Kelvin?
Add 273.15 to the Celsius value. For example, 25 °C = 25 + 273.15 = 298.15 K.
What is 0 °C in Kelvin?
0 °C equals 273.15 K — the freezing point of water on both scales.
What is absolute zero in Celsius?
Absolute zero is 0 K, which equals −273.15 °C. Temperature cannot go below this on either scale.
Why is the Kelvin step the same as Celsius?
Both scales share the same magnitude per degree by definition — only the zero point differs, so a 1-degree change is identical.
Should I write °K or just K?
Just K. Kelvin is an absolute unit, so it does not use the degree symbol — write 300 K, not 300 °K.