Kelvin to Celsius Converter
Type a temperature in kelvin to get degrees Celsius. 300 K, a common “room temperature” in physics, is 26.85 °C.
300 K =
26.85°C
300 kelvins is 26.85 degrees Celsius.
- In Fahrenheit
- 80.33 °F
How this works: Method, 4 sources, Checked against 1 worked example,
How this works
Method
Subtract 273.15 from the kelvin value. Nothing gets multiplied, since one kelvin is exactly as large as one Celsius degree; the scales are just shifted. Full method
Sources
How it’s tested
One worked example for this page is checked by automated tests before every release: given the inputs, the tool must show the expected answer.
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Changes
- Ask understands “5 ft 9 in to cm” and “2 cups of flour in grams” and answers at once, and a decimal comma (“2,5”) reads as 2.5.
- First published: 89 everyday units across ten quantities, with 58 pages for common pairs such as cm to inches and Celsius to Fahrenheit.
How to convert kelvin to Celsius
Subtract 273.15 from the kelvin value. Nothing gets multiplied, since one kelvin is exactly as large as one Celsius degree; the scales are just shifted.
For 77 K, a common figure in cryogenics: 77 − 273.15 = −196.15 °C. For a hot filament at 1,000 K: 1,000 − 273.15 = 726.85 °C. Any value under 273.15 K comes out below zero Celsius.
The same subtraction works for colour temperature written in kelvins, although there the number describes the hue of a light source rather than how hot anything feels.
°C = K − 273.15
- Celsius temperature is defined from thermodynamic temperature as t/°C = T/K − 273.15, and the two units have the same magnitude. Source: BIPM, The International System of Units (SI Brochure, 9th edition).
- The Sun’s nominal effective temperature is 5,772 K, as adopted by the International Astronomical Union. Source: IAU 2015 Resolution B3, nominal solar and planetary values (Prša et al.).
How to estimate kelvin to Celsius in your head
Take away 273, or 270 if you only need a rough idea. 310 K becomes about 37 °C (exactly 36.85), body temperature. Above a few thousand kelvins the offset hardly matters: 5,772 K is 5,499 °C, so “about 5,500” is a fair reading.
Near the bottom of the scale the reverse is true and the offset is almost all of the answer. Liquid helium at 4.2 K is −268.95 °C: a reading that looks tiny in kelvins sits just a few degrees above the coldest point physics allows, which is why low-temperature work is almost always reported in kelvins.
Kelvin to Celsius table
From the coldest liquids to the surface of the Sun.
| Kelvins (K) | Degrees Celsius (°C) | Reference point |
|---|---|---|
| 0 | -273.15 | absolute zero |
| 4.2 | -268.95 | helium boils |
| 20.3 | -252.85 | hydrogen boils |
| 77.35 | -195.8 | nitrogen boils |
| 194.65 | -78.5 | dry ice sublimes |
| 233.15 | -40 | |
| 273.15 | 0 | water freezes |
| 293.15 | 20 | |
| 300 | 26.85 | physics “room temperature” |
| 310.15 | 37 |
Show all 14 rowsShow fewer
| 373.15 | 100 | water boils (1 atm) |
| 1,000 | 726.85 | |
| 2,700 | 2,426.85 | warm-white bulb colour |
| 5,772 | 5,498.85 | Sun’s surface |
Frequently Asked Questions
What is 0 K in Celsius?
0 K is −273.15 °C, absolute zero. It can be approached in laboratories but never reached.
What does 2700 K on a light bulb mean?
It is a colour temperature: the bulb’s light matches the colour of an ideal glowing body at 2,700 K. The bulb itself is far cooler than that.
Can a kelvin temperature be negative?
Not on the ordinary scale. Kelvin starts at absolute zero, so every real temperature is zero or positive; any negative kelvin input is rejected.