Direct answer

Celsius vs Kelvin: What’s the Difference?

Same degree size, different zero. 0 °C = 273.15 K. Science and weather answer with converter links.

Question

What is the difference between Celsius and Kelvin?

Both use the same degree size. Kelvin starts at absolute zero, so K = °C + 273.15.

0 °C

273.15 K

Formula

K = °C + 273.15

Degree size

Same for °C and K

A 1 °C change equals a 1 K change — only the zero points differ.

0 K is absolute zero (−273.15 °C). Water freezes at 273.15 K and boils at 373.15 K at standard pressure.

Weather reports use Celsius; thermodynamics and physics usually use Kelvin.