CalcPairsCelsius to Kelvin Converter (°C to K)
25 °C is 298.15 K. Kelvin and Celsius use the same size of degree — only the zero moves: K = °C + 273.15, with 0 K at absolute zero, −273.15 °C, the coldest temperature that can exist.
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How this conversion works
Science runs on Kelvin because its zero is real: at 0 K, thermal motion stops, and ratios start to mean something (600 K genuinely is twice as hot as 300 K, which is never true in Celsius). Type either side — room temperature 20 °C is 293.15 K, the Sun's surface is about 5,778 K, and deep space sits near 2.7 K.
Because the two scales share a degree size, this is the simplest conversion on the site: one addition, no multiplication. The table below runs from absolute zero up through laboratory temperatures.
The exact formula
K = °C + 273.15 · °C = K − 273.15
The kelvin is the SI unit of temperature. Its zero is absolute zero; its degree is exactly the Celsius degree. Note the style: kelvin takes no degree symbol — 298.15 K, never 298.15 °K.
Celsius to Kelvin conversion table
| Celsius (°C) | Kelvin (K) |
|---|---|
| -273.15 | 0 |
| -100 | 173.15 |
| -50 | 223.15 |
| -40 | 233.15 |
| 0 | 273.15 |
| 10 | 283.15 |
| 20 | 293.15 |
| 25 | 298.15 |
| 30 | 303.15 |
| 37 | 310.15 |
| Celsius (°C) | Kelvin (K) |
|---|---|
| 50 | 323.15 |
| 100 | 373.15 |
| 200 | 473.15 |
| 300 | 573.15 |
| 500 | 773.15 |
| 1000 | 1273.15 |
Frequently asked questions
Why is it 273.15 and not 273?
The 0.15 is measured, not decorative: absolute zero sits at −273.15 °C on the Celsius scale as defined by the triple point of water (0.01 °C = 273.16 K). Using 273 alone throws answers off by a visible 0.15.
Can Kelvin be negative?
No. 0 K is the floor of temperature itself; the converter will still do the arithmetic if you type a negative Kelvin value, but no physical temperature corresponds to it.
How do I convert Fahrenheit to Kelvin?
Go through Celsius: K = (°F − 32) × 5/9 + 273.15. Or convert °F to °C on the sister page, then add 273.15 here.