Kelvin to Celsius Converter (K to °C)

Physics papers, spacecraft data and cryogenic equipment report temperature in kelvins, the SI base unit, while most readers picture heat and cold in degrees Celsius. Subtracting 273.15 converts one to the other. The two scales use steps of the same size, so a change of ten kelvins is also a change of ten degrees Celsius; only the starting point differs.

Very cold readings are where Celsius becomes awkward: liquid helium boils at about 4.2 K, which is roughly −269 °C, and the afterglow of the Big Bang measures about 2.725 K. Kelvins count up from zero, so 4 K is plainly twice as far from absolute zero as 2 K, which the Celsius figures hide. Hot readings convert the same way, with the Sun's surface at about 5,772 K, or about 5,499 °C.

How to use this tool

1. Type a value in the Kelvin box to see it in degrees Celsius, or type in the Celsius box to convert the other way.
2. Press ⇄ to swap the two units, or Load example for a typical value.
3. Check the charts below for common values; for other units, open the Temperature converter.

Formula

°C = K − 273.15

K = °C + 273.15

The scales have different zero points, so the formula adds or subtracts an offset as well as multiplying.

Example

Two conversions worked with the same factors the converter uses:

77 K = -196.15 °C

-269 °C = 4.15 K

Kelvin to Celsius chart

Common values from kelvins to degrees Celsius, rounded to four decimal places.

Celsius to Kelvin chart

The reverse direction for values people often look up.

Temperatures usually quoted in kelvins

Quick mental estimate

Subtract 273 and you are within 0.15 degrees: 300 K → 27 °C, exactly 26.85 °C. Anything below 273.15 K comes out negative, so 77 K → 77 − 273 = −196 °C.

Use the converter or the charts when the exact figure matters.

The two units

Kelvin (K): The kelvin is the SI base unit of thermodynamic temperature, defined since 2019 by fixing the Boltzmann constant at exactly 1.380649 × 10⁻²³ J/K. The scale starts at absolute zero (0 K), and 0 °C is exactly 273.15 K.

Celsius (°C): Celsius temperature is the kelvin value minus exactly 273.15. At standard atmospheric pressure, pure water freezes near 0 °C and boils near 100 °C; these water temperatures are reference points, not the modern definition of the scale.