Celsius to Kelvin (°C to K)

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Celsius°C

Kelvin

274.15

Formula: Kelvin = Celsius + 273.15

Common Conversions

Celsius (°C)	Kelvin (K)
-273.15	0
-200	73.1500
-196	77.1500
-100	173.15
-78	195.15
-40	233.15
-20	253.15
0	273.15
10	283.15
20	293.15
25	298.15
30	303.15
37	310.15
50	323.15
100	373.15
200	473.15
500	773.15
1000	1273.15
2000	2273.15
5000	5273.15

What Is Celsius TO Kelvin?

To convert Celsius to Kelvin, simply add 273.15 to the Celsius temperature. The formula is K = °C + 273.15. For example, 25 °C equals 298.15 K because 25 + 273.15 = 298.15. The Kelvin scale is the SI base unit of thermodynamic temperature and is used extensively in physics, chemistry, engineering, and astronomy. Unlike Celsius and Fahrenheit, the Kelvin scale starts at absolute zero — the theoretical point where all molecular motion ceases — making it an absolute temperature scale with no negative values. This property makes Kelvin indispensable for gas law calculations such as the ideal gas law (PV = nRT), where temperature must be in Kelvin. In astrophysics, the surface temperatures of stars are expressed in Kelvin — the Sun's photosphere is approximately 5778 K (about 5505 °C). Cryogenic research and superconductor studies frequently reference Kelvin values near absolute zero, such as liquid nitrogen at 77 K (-196 °C) and liquid helium at 4.2 K (-268.95 °C). The Celsius and Kelvin scales share the same degree size, so a temperature difference of 1 °C is exactly equal to a difference of 1 K. This makes conversion between them the simplest of all temperature conversions.

Formula

The Celsius-to-Kelvin formula is K = °C + 273.15. This is the simplest temperature conversion because both scales use the same degree size — one degree Celsius equals one Kelvin. The only difference is the zero point: 0 °C corresponds to the freezing point of water (273.15 K), while 0 K is absolute zero (-273.15 °C). Therefore, you only need to add the offset of 273.15. Worked example: to convert -196 °C (the boiling point of liquid nitrogen) to Kelvin, compute -196 + 273.15 = 77.15 K. Another example: room temperature at 20 °C becomes 20 + 273.15 = 293.15 K. No multiplication or division is required, making this conversion straightforward and error-free.

Best For:

Performing ideal gas law calculations in chemistry and physics classes
Expressing stellar and planetary temperatures in astrophysics research
Working with cryogenic systems and superconductor experiments
Calibrating scientific instruments that require absolute temperature readings
Converting laboratory Celsius measurements for thermodynamic equations

How to Celsius TO Kelvin

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Frequently Asked Questions

The formula is K = °C + 273.15. Simply add 273.15 to any Celsius temperature to get the Kelvin equivalent.

Absolute zero is 0 K, which equals -273.15 °C. It is the lowest possible temperature where all thermal motion of particles theoretically stops.

The precise offset is 273.15 because the triple point of water was defined as exactly 273.16 K (0.01 °C). This makes the ice point of water 273.15 K (0 °C). Using 273 is a common approximation but introduces a 0.15-degree error.

Yes. Both scales use the same increment size. A change of 1 °C is identical to a change of 1 K. The only difference is where the zero point falls.

You must use Kelvin for thermodynamic equations like the ideal gas law (PV = nRT), Stefan-Boltzmann radiation law, and any formula where temperature appears as a ratio or product. Celsius can produce incorrect results in these calculations because of its offset zero.