1 celsius equals 274.15 kelvin. Enter a value below to convert instantly.
Celsius to kelvin is the simplest temperature conversion: add 273.15. The two scales use degrees of identical size, so nothing is scaled — only the zero point moves, from water's freezing point to absolute zero.
Need the other direction? Convert kelvin to celsius →
K = °C + 273.15
Not a simple multiplication. These scales have different zero points, so the conversion applies an offset as well as a ratio.
| Celsius (°C) | Kelvin (K) |
|---|---|
| -40 | 233.15 |
| -20 | 253.15 |
| 0 | 273.15 |
| 10 | 283.15 |
| 20 | 293.15 |
| 32 | 305.15 |
| 37 | 310.15 |
| 50 | 323.15 |
| 98.6 | 371.75 |
| 100 | 373.15 |
The ideal gas law and every equation derived from it require absolute temperature. Substituting 25 °C instead of 298.15 K does not give a slightly wrong answer — it gives a nonsensical one, and at temperatures near or below 0 °C it produces negative or infinite results.
Bulbs and camera white-balance settings are specified in kelvin: 2700 K for warm domestic light, 5000–6500 K for daylight. These are not room temperatures — they describe the spectrum of an idealised radiator at that temperature — but they are stated in the same unit.
Liquid nitrogen boils at 77 K (−196 °C) and superconducting transitions are quoted in kelvin. Below about 100 K, Celsius values are large negative numbers that are awkward to compare, which is why the field works in kelvin throughout.
Carnot efficiency depends on the ratio of absolute temperatures. A heat engine between 100 °C and 20 °C has an efficiency ceiling based on 373.15 K and 293.15 K — using the Celsius numbers directly gives an answer that is wrong by a factor of several.
Values people actually look up, with the reason each one comes up. Every figure is calculated with the same engine as the converter above.
| Celsius (°C) | Kelvin (K) | What it is |
|---|---|---|
| -273.15 | 0 | Absolute zero |
| -196 | 77.15 | Liquid nitrogen boils |
| -18 | 255.15 | Standard freezer temperature |
| 0 | 273.15 | Water freezes |
| 20 | 293.15 | Room temperature |
| 25 | 298.15 | Standard laboratory reference |
| 37 | 310.15 | Body temperature |
| 100 | 373.15 | Water boils at sea level |
The kelvin is an SI base unit, defined since 2019 by fixing the Boltzmann constant at 1.380 649 × 10⁻²³ J/K. Its zero is absolute zero — the point where a system holds no thermal energy to give up — so kelvin values are never negative. The Celsius scale is defined as the kelvin scale offset by exactly 273.15, which is why 0 °C is 273.15 K rather than a round number. Because the degree sizes match exactly, a temperature *difference* is numerically identical in both: a 5 °C rise is a 5 K rise.
The 273.15 offset is exact, so no precision is lost. What changes is the number of significant figures: 25 °C has two, but 298.15 K looks like five. Carry the extra digits through a calculation and round the final answer back to the precision of the original measurement. Note also that kelvin takes no degree sign and no plural — 300 K, not 300 °K or 300 kelvins in symbol form.
The kelvin has had no degree sign since 1967. It is written 300 K, and spoken as '300 kelvin', not '300 degrees kelvin'.
PV = nRT needs absolute temperature. Using °C where K is required is one of the most common errors in introductory thermodynamics and chemistry, and it fails loudly only when the Celsius value is negative.
A difference of 10 °C is a difference of 10 K. The offset applies to absolute readings, never to intervals.
Content on this page last reviewed 12 August 2026. Spotted an error? Report it — see also how these values are calculated.
1 °C expressed in every other temperature unit on this site.
The celsius (°C) is a Metric unit of temperature.
The kelvin (K) is a SI unit of temperature.
The Celsius scale is defined as exactly 273.15 below the kelvin scale. The figure traces back to the historical definition using the triple point of water at 273.16 K; using 273 is an approximation that costs you 0.15 K.
Not on the thermodynamic scale. Zero kelvin is absolute zero, the lowest possible temperature, so a negative result means an arithmetic error somewhere upstream.
Yes, exactly. The two scales use identically sized degrees, so temperature differences, rates and coefficients are numerically the same in both — only absolute readings differ.
One celsius equals 274.15 kelvin.
K = °C + 273.15
One kelvin equals -272.15 celsius.
This conversion is common when cooking, weather, medical readings, and science experiments.