Convert Celsius to Kelvin
Convert Celsius to Kelvin instantly. Formula, worked examples and a full reference table from -40° upward.
Last updated
Converting Celsius to Kelvin is not a simple multiplication, because the two scales have different zero points as well as different degree sizes. The conversion needs both a scaling step and an offset.
Enter any temperature above and the result updates as you type. The formula and a reference table covering everyday temperatures follow below.
Temperature is the one category where conversion is not multiplication. The scales have different zero points as well as different degree sizes, so every conversion needs an offset too, and no single "factor" exists to quote. It is also the conversion people most often need at speed — a weather forecast, an oven setting, a fever reading — which is why the approximations are worth knowing: doubling Celsius and adding 30 gets you within a couple of degrees of Fahrenheit across everyday temperatures.
Celsius to Kelvin formula
To go the other way, use °C = K − 273.15.
About these units
The Celsius scale sets zero at the freezing point of water and 100 at its boiling point, both at standard atmospheric pressure.
Kelvin starts at absolute zero, the point where thermal motion stops. It uses Celsius-sized degrees and takes no degree symbol.
Sources
Celsius to Kelvin conversion table
| Celsius | Kelvin |
|---|---|
| -40 °C | 233.15 K |
| -20 °C | 253.15 K |
| -10 °C | 263.15 K |
| 0 °C | 273.15 K |
| 10 °C | 283.15 K |
| 20 °C | 293.15 K |
| 25 °C | 298.15 K |
| 30 °C | 303.15 K |
| 37 °C | 310.15 K |
| 40 °C | 313.15 K |
| 50 °C | 323.15 K |
| 100 °C | 373.15 K |
Frequently asked questions
How many kelvins are in a celsius? +
Temperature scales cannot be compared this way, because they do not share a zero point. Use the formula K = °C + 273.15 instead.
What is 25 °C in K? +
25 °C equals 298.15 K. Apply the formula K = °C + 273.15.
How do I convert kelvin back to celsius? +
Use °C = K − 273.15. The converter above handles both directions, or see our dedicated Kelvin to Celsius page.
How accurate is this celsius to kelvin conversion? +
The scale definitions are exact — the relationships between Celsius, Fahrenheit and Kelvin are fixed by definition rather than measured — and the calculation carries full double precision. Only the displayed result is rounded, so what you read is a rounded view of an exact conversion rather than a conversion performed on rounded numbers.
Is there a quick way to estimate °C to K in my head? +
Kelvin and Celsius differ by a constant 273.15, so the shortcut is simply to add or subtract 273 and accept a sixth of a degree of error.