Kelvin (the SI absolute temperature scale) and Celsius are offset by exactly 273.15 degrees.
How it works
Subtracting 273.15 from Kelvin gives Celsius; adding 273.15 to Celsius gives Kelvin back. Type into either field and the other updates instantly.
What this does not include
This does not include Fahrenheit — for that, use this site’s full temperature converter, which covers all three scales on one page.
How to use this calculator
- Enter a value in either Kelvin or Celsius — the other field fills in automatically.
Frequently asked questions
Why can’t Kelvin go below zero?
Zero Kelvin is absolute zero, the theoretical point where all thermal motion stops — there’s no temperature colder than that, so negative Kelvin values aren’t physically meaningful.
Why is the offset exactly 273.15?
It’s the internationally defined relationship between the Kelvin and Celsius scales, fixing 0°C at exactly 273.15 K.
Where is Kelvin most commonly used?
Scientific and engineering contexts, especially physics and chemistry, where an absolute temperature scale (with no negative values) is needed for calculations.
