Celsius to Kelvin conversion formula: Kelvin = Celsius + 273.15.
To convert Celsius to Kelvin, add 273.15 to Celsius because the absolute zero is theoretically possible at 0 Kelvin or -273.15 °C.
For example: To convert 30 °C to Kelvin, add 273.15, that is 30 + 273.15 = 303.15 K
Celsius (centigrade) is a temperature scale with the freezing point of water is 0 degree and the boiling point of water is 100 degrees under standard atmospheric pressure (101.325 kPa). The absolute zero temperature is -273.15 °C. The symbol for Celsius is "°C".
Kelvin is the base unit of temperature in metric system and formally defined as 1/273.16 of the thermodynamic temperature of the triple point of pure water. For Kelvin temperature scale, the freezing point of water is 273.15 K and boiling point is 373.15 K. The absolute zero is defined to be 0 Kelvin. The symbol for Kelvin is "K".