Temperature conversion
Celsius to Kelvin (°C to K)
Convert Celsius to Kelvin using K = C + 273.15.
Celsius to Kelvin conversion chart
| Celsius | Kelvin |
|---|---|
| -40 °C | 233.15 K |
| -30 °C | 243.15 K |
| -20 °C | 253.15 K |
| -10 °C | 263.15 K |
| -5 °C | 268.15 K |
| 0 °C | 273.15 K |
| 5 °C | 278.15 K |
| 10 °C | 283.15 K |
| 15 °C | 288.15 K |
| 18 °C | 291.15 K |
| 20 °C | 293.15 K |
| 22 °C | 295.15 K |
| 25 °C | 298.15 K |
| 28 °C | 301.15 K |
| 30 °C | 303.15 K |
| 35 °C | 308.15 K |
| 37 °C | 310.15 K |
| 40 °C | 313.15 K |
| 50 °C | 323.15 K |
| 100 °C | 373.15 K |
| 180 °C | 453.15 K |
How to convert by hand
K = C + 273.15
Temperature scales have different zero points, so you cannot simply multiply — the offset has to be applied as well. That is why °C and K do not scale proportionally.
Worked example: 18 °C × the formula above = 291.15 K .
Related conversions
About Celsius and Kelvin
Temperature is the one conversion that is not a simple multiplication: the scales start at different points, so an offset applies as well as a ratio.
Celsius
Metric (SI derived)Zero at the freezing point of water, 100 at its boiling point at sea level.
Commonly used for: Weather and cooking in most of the world.
Kelvin
Metric (SI)The SI base unit of temperature, starting at absolute zero. One kelvin is the same size as one degree Celsius.
Commonly used for: Science and engineering, where negative temperatures are inconvenient.
Questions
How do you convert Celsius to Kelvin?
Use the formula K = C + 273.15. For example, 10°C becomes 283.15K.
What is -5 °C in K?
-5°C = 268.15 K. Type any value into the converter above to get an exact answer.
How do I convert Kelvin back to Celsius?
Use our Kelvin to Celsius converter, which applies the inverse formula.
Is this converter accurate?
Yes. Linear conversions use the internationally agreed factors published by NIST (SP 811), and temperature conversions use the exact defining formulas. Calculations run at full double precision and are only rounded for display.
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