Celsius to Kelvin formula
K = °C + 273.15
Example: 25°C + 273.15 = 298.15K
About the Celsius scale
The Celsius scale is widely used for everyday temperatures and scientific measurements. Under standard atmospheric pressure, water freezes at 0°C and boils at 100°C. The Celsius and Kelvin scales use the same size temperature increment, but their zero points are offset by 273.15 degrees.
About the Kelvin scale
The kelvin is the SI unit of thermodynamic temperature and is widely used in physics, chemistry, and astronomy. Its zero point, 0 K, is absolute zero, the lowest possible temperature on the standard thermodynamic scale.
One kelvin has the same size as one degree Celsius, but the scales use different zero points. This makes Celsius to Kelvin conversion a simple offset of 273.15.
Reference table
| Celsius | Kelvin |
|---|---|
| −273.15°C | 0K (absolute zero) |
| 0°C | 273.15K (freezing) |
| 20°C | 293.15K (room temperature) |
| 37°C | 310.15K (approximate body temperature) |
| 100°C | 373.15K (boiling) |
Need the reverse direction? See Kelvin to Celsius.
Frequently asked questions
Why is Celsius to Kelvin just addition?
Celsius and Kelvin use the same size temperature increment, but their zero points are different. Absolute zero is 273.15 degrees below 0°C, so converting Celsius to Kelvin simply means adding 273.15.
What is absolute zero in Celsius?
Absolute zero is 0 K, which is exactly −273.15°C. For ordinary temperature conversion, Celsius values are entered at −273.15°C or above.
Do Celsius and Kelvin ever show the same number?
No. For corresponding temperatures, the Kelvin value is always 273.15 greater than the Celsius value. For example, 0°C is 273.15 K and −273.15°C is 0 K.