Celsius (°C) to Kelvin (K)
To convert Celsius to Kelvin, simply add 273.15 to the temperature in Celsius. Kelvin is the absolute temperature scale used in science, engineering, and physics. Unlike Celsius or Fahrenheit, the Kelvin scale has no negative values — 0 K is absolute zero, the lowest possible temperature at −273.15 °C. Kelvin is essential for thermodynamic calculations and is the SI base unit for temperature.
Frequently asked questions
Add 273.15 to the Celsius value. For example, 0 °C = 273.15 K (freezing point of water), and 100 °C = 373.15 K (boiling point of water). The formula is: K = °C + 273.15.
Kelvin is an absolute scale starting at the lowest physically possible temperature — absolute zero. This makes it essential for thermodynamic equations such as the ideal gas law (pV = nRT), where negative temperatures would produce nonsensical results. At GCSE and A-level, Kelvin is introduced in chemistry and physics for exactly this reason.
Room temperature is typically 20–22 °C, which converts to 293.15–295.15 K. In scientific literature, room temperature is often standardised at 298 K (25 °C) for consistency in reporting experimental conditions.
Yes — the magnitude of one degree Celsius and one Kelvin is identical. A temperature difference of 1 °C is exactly the same as a difference of 1 K. Only the zero points differ: Celsius is set at the freezing point of water, while Kelvin starts at absolute zero.