Kelvin to Celsius Converter

Convert whole or decimal kelvin values to Celsius and reverse the calculation from either field.

Temperature to convert
Converted temperature

How the converter works

A kelvin scale descending by a fixed offset to a Celsius scale

Convert kelvin to Celsius by subtracting 273.15. The calculator starts with 293.15 K = 20 °C, accepts decimal values, and can also work backwards from the Celsius field.

The zero point moves; the interval stays the same

t°C=TK273.15t_{\degree C} = T_{\mathrm{K}} - 273.15

Kelvin and Celsius use equal-sized intervals, so subtracting the offset is the only operation. For the reverse direction, use TK=t°C+273.15T_{\mathrm{K}} = t_{\degree C} + 273.15.

The kelvin is the SI base unit of thermodynamic temperature. Its symbol is K without a degree sign. The US National Institute of Standards and Technology gives the same conversion and notation.

Reference values that reveal a wrong offset

293.15 K equals 20 °C. This room-temperature value is a useful first check.

273.15 K equals 0 °C. If the result is 273.15 instead, the offset was not subtracted.

0 K equals -273.15 °C. This is absolute zero, the lower boundary of ordinary thermodynamic temperature.

Enter the scale you already have

Type kelvins on the left and read Celsius on the right. Editing the result performs the reverse conversion. The middle button swaps both scales and values, while the selectors also offer Fahrenheit and Réaumur.

A decimal comma or point is accepted. The display keeps at most two decimal places and removes trailing zeroes.

Temperature changes need no offset

A rise from 290 K to 295 K is a rise of 5 K and also 5 °C. Subtract 273.15 only when converting a complete temperature reading.

The conversion is exact, but it cannot improve the accuracy of the original measurement. Physical reference points such as water boiling can also change with pressure.

The calculator still performs arithmetic for negative kelvin inputs. Such a result falls outside the ordinary thermodynamic temperature scale.

Kelvin to Celsius questions

The most common mistakes concern the offset, notation, and temperature differences.

What is the exact kelvin-to-Celsius formula?

Subtract 273.15: °C = K - 273.15.

What is 300 K in Celsius?

300 K equals 26.85 °C.

Should kelvin be written with a degree sign?

No. Write 300 K, not 300 °K.

Can a positive kelvin value become negative Celsius?

Yes. Every temperature below 273.15 K is below 0 °C.

Is a change of 1 K equal to a change of 1 °C?

Yes. The interval sizes are identical; only the scale origins differ.

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