Celsius to Kelvin
Convert Celsius to kelvin with the offset K = C + 273.15. Absolute zero is 0 K, which is -273.15 °C. The engine rejects temperatures below that.
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How to convert Celsius to kelvin
- Enter the temperature in Celsius. The default is 1.
- Keep From as Celsius and To as Kelvin, or pick Fahrenheit.
- Read kelvin. Add 273.15 to the Celsius value.
- Swap units to convert kelvin back to Celsius. Values below absolute zero show an error.
Celsius degree
Temperature (offset to kelvin)
| Kelvin | SI thermodynamic temperature, 0 K is absolute zero |
|---|---|
| Celsius | K = C + 273.15, same degree size as kelvin |
| Absolute zero | 0 K = -273.15 °C = -459.67 °F |
| Fahrenheit | F = C × 9/5 + 32, on the same list |
| Water | 0 °C = 273.15 K at the ice point on this scale |
| Not weather | This is not a forecast or a live sensor |
What Celsius to kelvin does
Celsius and kelvin share the same degree size. They differ by a fixed offset of 273.15. This spoke adds that offset. A room at 20 °C is 293.15 K. The engine converts through kelvin internally, so Fahrenheit on the same list stays consistent. A value that would fall below 0 K is rejected.
Fahrenheit as the other everyday scale is on fahrenheit to celsius and the temperature converter.
Celsius and kelvin offset
K = C + 273.15. C = K - 273.15. F = C × 9/5 + 32. There is no multiply-only factor between C and K because 0 °C is not 0 K. Do not treat 20 °C as 20 K.
Absolute zero and degree size
Absolute zero is the point where thermodynamic temperature is zero. ITS-90 and other lab scales refine fixed points. This page uses the conventional 273.15 offset that SI practice uses for this converter. A kelvin interval equals a Celsius interval. A 5 K rise is a 5 °C rise.
When to convert Celsius to kelvin here
Move a lab Celsius reading into kelvin, check a datasheet that quotes K, or swap to Fahrenheit. Leave weather apps and thermocouple polynomials off this form.
What this page does not do
It does not forecast weather. It does not convert a temperature interval that you already expressed as a difference unless you type that difference as a kelvin or Celsius delta with care: a 10 °C change is a 10 K change, but adding 273.15 to a delta is wrong. Input stays in this tab.