How to convert Celsius to Kelvin
K = °C + 273.15
Apply the operations in the order shown. This formula converts a Celsius temperature reading to Kelvin, not a temperature difference. The source reading must be at least -273.15 °C, the absolute-zero limit.
Worked examples
0 °C ≈ 273.15 K
0 + 273.15 ≈ 273.15
Water’s familiar freezing reference near standard atmospheric pressure.
100 °C ≈ 373.15 K
100 + 273.15 ≈ 373.15
Water’s familiar boiling reference near standard atmospheric pressure; actual boiling temperature changes with pressure.
Frequently asked questions
Can I use °C to K for a temperature difference?
For an interval, use only the degree-size ratio and omit any offset. This calculator converts scale readings. Kelvin and Rankine start at absolute zero; Celsius and Fahrenheit have different zero points.