Celsius (°C) to Kelvin (K)
To convert Celsius to Kelvin, add 273.15. Kelvin is the absolute temperature scale used in science and engineering. Unlike Celsius or Fahrenheit, there are no negative Kelvin values — 0 K is absolute zero, the coldest possible temperature at −273.15 °C. Kelvin is the SI base unit for temperature and is essential in thermodynamics, chemistry, and physics courses from high school through university.
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 is essential for thermodynamic equations such as the ideal gas law (PV = nRT), used in high school AP Chemistry and college courses. Negative temperatures would produce nonsensical results in these equations, which is why Kelvin is required.
Room temperature is typically 68–72 °F (20–22 °C), which equals approximately 293–295 K. In scientific literature and lab settings, room temperature is often standardized at 298 K (25 °C or 77 °F).
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.