kelvin to celsius converter

How to convert kelvin to celsius

Celsius is kelvin minus 273.15. The size of the degree is the same, which is why a temperature difference does not subtract 273.15. A reading does. Zero kelvin, absolute zero, is −273.15 °C. The freezing point of water, 273.15 K, is 0 °C. The boiling point, 373.15 K, is 100 °C. Room temperature around 293.15 K is 20 °C. If you subtract 273 instead of 273.15 you are off by 0.15 degrees, which is the entire reason the constant has a fractional part.

Science and engineering data that were logged in kelvin and have to be read by someone who thinks in Celsius. Color temperature in kelvin (a 3000 K lamp) is not a room temperature. Converting it to Celsius produces a huge number that is technically the same formula and physically the wrong question. The formula does not know why you asked.

Exact formula

Formula°C = K − 273.15

°C = K − 273.15 One K is -272.15 °C. Ten K is -263.15 °C. The worked example below uses that same conversion.

Conversion table

The kelvin column runs from 0 K (-273.15 °C) through 5778 K (5504.85 °C).

Worked example: Kelvin to Celsius

Water's old standard freezing point, 273.15 K, is 0 °C. Subtract 273.15 from a reading. Do not subtract it from a temperature difference, because the degree is the same size. Absolute zero, 0 K, is -273.15 °C. A lab value of 300 K is 26.85 °C. Using 273 instead of 273.15 is off by 0.15 degrees on every reading. A 3000 K lamp is a color temperature. The arithmetic still runs and the physical question is wrong. Fahrenheit needs a further 9/5 and a 32 after you reach Celsius.

Pitfalls for kelvin to celsius

• Do not subtract 273.15 from a delta. A rise of 10 K is a rise of 10 °C.
• 273 is the integer shortcut. The defined offset is 273.15.
• Fahrenheit needs a further ×9/5 + 32 after you reach Celsius. This page stops at Celsius.
• Negative kelvin is not a temperature on this scale. The box will still do the arithmetic.