By Tim King · Updated 19 September 2026

Kelvin to Celsius and Celsius to Kelvin

Live Two-Way Temperature Conversion With Formula, Worked Examples and Tables

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kelvins to degrees Celsius formula

°C = K − 273.15

Take the kelvins figure and subtract 273.15.

kelvins to degrees Celsius table

kelvins (K)	degrees Celsius (°C)
0	-273.15
1	-272.15
4.2	-268.95
10	-263.15
20	-253.15
50	-223.15
77	-196.15
100	-173.15
150	-123.15
195	-78.15
200	-73.15
250	-23.15
273.15	0
280	6.85
290	16.85
293.15	20
298.15	25
300	26.85
310	36.85
350	76.85
373.15	100
400	126.85
500	226.85
1,000	726.85
2,700	2,426.85
5,778	5,504.85

Common kelvins to degrees Celsius conversions

0 K = -273.15 °C. 0 kelvins is -273.15 degrees Celsius.

273.15 K = 0 °C. 273.15 kelvins is 0 degrees Celsius.

298.15 K = 25 °C. 298.15 kelvins is 25 degrees Celsius.

300 K = 26.85 °C. 300 kelvins is 26.85 degrees Celsius.

373.15 K = 100 °C. 373.15 kelvins is 100 degrees Celsius.

degrees Celsius to kelvins formula

K = °C + 273.15

Take the degrees Celsius figure and add -273.15.

degrees Celsius to kelvins table

degrees Celsius (°C)	kelvins (K)
-273.15	0
-200	73.15
-100	173.15
-78.5	194.65
-50	223.15
-40	233.15
-20	253.15
-10	263.15
0	273.15
4	277.15
10	283.15
15	288.15
20	293.15
25	298.15
30	303.15
37	310.15
40	313.15
50	323.15
75	348.15
100	373.15
150	423.15
200	473.15
300	573.15
500	773.15
1,000	1,273.15

Common degrees Celsius to kelvins conversions

0 °C = 273.15 K. 0 degrees Celsius is 273.15 kelvins.

20 °C = 293.15 K. 20 degrees Celsius is 293.15 kelvins.

25 °C = 298.15 K. 25 degrees Celsius is 298.15 kelvins.

37 °C = 310.15 K. 37 degrees Celsius is 310.15 kelvins.

100 °C = 373.15 K. 100 degrees Celsius is 373.15 kelvins.

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How the Kelvin To Celsius works

Convert kelvin to Celsius, or the other way, in one step. Type a temperature in kelvin and get degrees Celsius as you type. The two scales use the same size of degree and differ only in where zero is, so the conversion is a single subtraction of 273.15. The table runs from absolute zero through laboratory and room temperatures to the surface of the sun. Press the swap button to go the other way.

Kelvin to Celsius: same degree, different zero

Kelvin and Celsius measure temperature in steps of exactly the same size. A rise of one kelvin is a rise of one degree Celsius. The scales differ only in where they put zero. Celsius puts it near the freezing point of water, a convenient everyday mark. Kelvin puts it at absolute zero, the point where a body has the least thermal energy physics allows, and nothing can ever be colder. Only on kelvin can a temperature be doubled or halved, so formulas insist on it.

The formula

°C = K − 273.15, and K = °C + 273.15.

The 273.15 is exact. Since the 2019 redefinition of the SI, the kelvin has been fixed through the Boltzmann constant, k = 1.380649 × 10⁻²³ J/K. Celsius is defined as kelvin minus exactly 273.15. Before 2019 the kelvin was tied to the triple point of water, 273.16 K or 0.01 °C, and that is where the odd-looking offset comes from. Kelvin takes no degree sign: 300 K, not 300 °K.

Worked examples

The first example is a chemistry data sheet quoting a value "at 298 K". 298 − 273.15 = 24.85 °C. The table was almost certainly measured at the standard 298.15 K, which is exactly 25 °C, and rounded. A kelvin figure ending in 3 or 8 is often a round Celsius number in disguise: 273 K is 0 °C, 293 K is 20 °C and 373 K is 100 °C.

The second example is a cryogenic dewar of liquid nitrogen at 77 K. 77 − 273.15 = −196.15 °C, usually quoted as −196 °C. Going the other way, a −78.5 °C dry-ice bath is −78.5 + 273.15 = 194.65 K.

A third example shows why the conversion matters in a formula. Gas at 20 °C heated to 40 °C has not doubled its temperature. In kelvin it went from 293.15 K to 313.15 K, a rise of 6.8%, so at constant pressure its volume grows by 6.8%, not 100%.

How many degrees Celsius is that kelvin figure?

Fahrenheit is included for comparison. Kelvin to Celsius and Fahrenheit, from absolute zero to the Sun's surface

Temperature	K	°C	°F
Absolute zero	0	−273.15	−459.67
Cosmic microwave background	2.725	−270.42	−454.76
Liquid helium boils	4.22	−268.93	−452.07
Liquid hydrogen boils	20.28	−252.87	−423.17
Liquid nitrogen boils	77.36	−195.79	−320.42
Liquid oxygen boils	90.19	−182.96	−297.33
YBCO superconductor transition	93	−180.15	−292.27
Coldest air on Earth, Vostok 1983	183.95	−89.2	−128.56
Dry ice sublimes	194.65	−78.5	−109.3
Celsius and Fahrenheit agree	233.15	−40	−40
0 °F	255.37	−17.78	0
Water freezes	273.15	0	32
Water at its densest	277.13	3.98	39.16
ISA sea-level standard	288.15	15	59
Laboratory room temperature	293.15	20	68
Chemistry standard state	298.15	25	77
Physics room temperature	300	26.85	80.33
Human body	310.15	37	98.6
Hottest air recorded, Death Valley 1913	329.85	56.7	134.06
Water boils at 1 atm	373.15	100	212
Oven for baking	453.15	180	356
Lead melts	600.61	327.46	621.43
Iron melts	1,811.15	1,538	2,800.4
Warm white bulb (colour temperature)	2,700	2,426.85	4,400.33
Tungsten melts	3,695.15	3,422	6,191.6
Sun's surface (IAU nominal)	5,772	5,498.85	9,929.93

How to read the result

The converter shows the Celsius figure live as you type, with the formula applied. Its own reference table steps through common kelvin values, including 273.15, 298.15 and 373.15, and the swap button reverses the direction for Celsius to kelvin.

Any kelvin value below 273.15 comes out negative in Celsius. That is correct: Celsius can go negative, and it is kelvin that cannot. A negative kelvin figure means a typing error or a Celsius value entered in the wrong box.

Where kelvin is used

Physics and chemistry. The ideal gas law, the Stefan–Boltzmann law, the Arrhenius equation and any ratio of temperatures need absolute temperature. Celsius in gives nonsense.
Standard conditions. IUPAC standard temperature is 273.15 K, 0 °C. Chemistry standard-state data use 298.15 K, 25 °C. The International Standard Atmosphere starts at 288.15 K, 15 °C, at sea level.
Engineering data sheets. Heat capacity in J/(kg·K), thermal conductivity in W/(m·K) and temperature coefficients per kelvin carry over to per degree Celsius unchanged.
Lighting and photography. Colour temperature is quoted in kelvin: 2,700 K for a warm white bulb, about 6,500 K for daylight.
Astronomy and space. Planet and star temperatures, and the 2.725 K cosmic microwave background, are always in kelvin.

Tips and pitfalls

Never convert a difference with the offset. A 15 K rise is a 15 °C rise. Subtracting 273.15 from a temperature difference is one of the most common exam and spreadsheet mistakes.
273 is close, not exact. Using 273 instead of 273.15 is a 0.15 degree error. That is harmless for weather but not for calibration or thermodynamic tables.
Absolute zero is a limit, not a target. Laboratories have reached billionths of a kelvin above it, never zero itself.

For the everyday conversions, use Celsius to Fahrenheit. For absolute temperatures in US data, kelvin to Fahrenheit converts directly without going through Celsius.

Sources: BIPM SI Brochure.

Checked against: 273.15 K = 0 °C

FAQ

What is the formula for kelvin to Celsius?

°C = K − 273.15. Subtract 273.15 from the kelvin figure. 300 K is 26.85 °C, 373.15 K is 100 °C and 0 K is −273.15 °C, absolute zero.

What is 300 K in Celsius?

300 K is 26.85 °C, or 80.33 °F — a warm room. Physics problems use 300 K as a convenient round-number room temperature; chemistry data use 298.15 K, which is exactly 25 °C.

Is 0 K colder than 0 °C?

Yes, by 273.15 degrees. 0 K is absolute zero, −273.15 °C, the lowest temperature possible. 0 °C is the freezing point of water, 273.15 K. Nothing can be cooled to 0 K; the coldest laboratory temperatures are billionths of a kelvin above it.

Does a 5,000 K light bulb get hot?

No. The kelvin figure on a bulb is its colour temperature — the temperature of a glowing body that would give the same colour of light — not its operating temperature. 5,000 K is 4,727 °C, hotter than any bulb; an LED runs at under 100 °C.

What is the formula for Celsius to kelvin?

K = °C + 273.15. Add 273.15 to the Celsius figure. 20 °C is 293.15 K, and 100 °C is 373.15 K. There is no multiplication because the two scales use the same size of degree.