Celsius to Kelvin Converter
Formula
K = °C + 273.15
Add 273.15 to a Celsius temperature to convert to Kelvin. The Kelvin scale starts at absolute zero (0 K = −273.15°C).
How to use
- Enter the temperature in the Celsius field.
- The Kelvin value updates automatically.
- Read the converted temperature in Kelvin.
Example
100°C converts to 373.15 K (100 + 273.15), the boiling point of water.
Frequently Asked Questions
What is 0°C in Kelvin?
0°C = 273.15 K (the freezing point of water).
What is absolute zero?
0 K = −273.15°C — the coldest possible temperature where all molecular motion stops.
Why is there no degree symbol with Kelvin?
By international convention, Kelvin temperatures are written as a plain number followed by K, such as 300 K, with no degree symbol. This is because the Kelvin is an absolute base unit of the SI system rather than a relative scale like Celsius or Fahrenheit. Saying or writing "degrees Kelvin" is technically incorrect, even though it's a common habit.
What is room temperature in Kelvin?
A comfortable room temperature of about 21°C converts to roughly 294 K, and most scientific work treats "standard" room temperature as 293.15 K (20°C) or 298.15 K (25°C). Because you simply add 273.15 to the Celsius value, everyday temperatures land in the high 200s to low 300s on the Kelvin scale. This range is useful to remember when reading physics or chemistry problems.