Kelvin (K) to Celsius (°C)
To convert Kelvin to Celsius, subtract 273.15. Kelvin temperatures appear in physics textbooks, chemistry labs, and astrophysics. Converting to Celsius gives a more relatable sense of the temperature — the surface of the Sun is about 5778 K, which works out to roughly 5505 °C. This conversion is a staple in high school and college science courses across the US.
Frequently asked questions
Subtract 273.15 from the Kelvin value. For example, 300 K − 273.15 = 26.85 °C, and 373.15 K = 100 °C (the boiling point of water at standard pressure).
0 K = −273.15 °C, which is absolute zero — the lowest temperature theoretically possible. At this point, atoms have minimal thermal energy. It cannot be reached in practice, though scientists have come within billionths of a degree.
Normal body temperature is 98.6 °F (37 °C), which equals 37 + 273.15 = 310.15 K. This value appears in biophysics and medical science where Kelvin is used in thermodynamic calculations.
The ideal gas law (PV = nRT) and other thermodynamic formulas require an absolute temperature scale. Using Celsius gives incorrect results because its zero point is arbitrary. In AP Chemistry and college courses, always convert temperatures to Kelvin before applying gas law equations.