Celsius to Kelvin
Convert Celsius to Kelvin instantly.
How to Convert Celsius to Kelvin
To convert Celsius to Kelvin, add 273.15: K = °C + 273.15. The Kelvin scale is the SI base unit of thermodynamic temperature and is used throughout science, engineering, and physics. Unlike Celsius and Fahrenheit, Kelvin has no degree symbol — you write 300 K, not 300°K. The Kelvin scale starts at absolute zero (0 K = −273.15°C), the theoretical point at which all molecular motion stops. There are no negative Kelvin temperatures.
Celsius to Kelvin Reference Chart
Common conversions: −273.15°C = 0 K (absolute zero) · 0°C = 273.15 K · 20°C = 293.15 K · 37°C = 310.15 K · 100°C = 373.15 K · 1000°C = 1273.15 K.
Frequently Asked Questions
What is the formula for Celsius to Kelvin?
K = °C + 273.15. The conversion is simple because the Kelvin and Celsius scales have the same size degree — they differ only in where zero is placed. Celsius zero is the freezing point of water; Kelvin zero is absolute zero.
What is 100°C in Kelvin?
100 + 273.15 = 373.15 K. This is the boiling point of water at standard atmospheric pressure (sea level). In scientific contexts, this is often rounded to 373 K.
Why is Kelvin used in science instead of Celsius?
Kelvin is used in science because it is an absolute temperature scale — it starts at the lowest possible temperature (absolute zero) and has no negative values. This makes it essential for thermodynamic calculations, gas law equations (PV = nRT), and quantum physics. Many physical laws only work correctly when temperature is expressed in Kelvin. Celsius and Fahrenheit, being relative scales, produce errors in these equations.
What is absolute zero in Celsius?
Absolute zero is −273.15°C (0 K). At this temperature, all classical thermal motion of atoms and molecules would cease. It is theoretically the coldest possible temperature. In practice, scientists have gotten within billionths of a degree of absolute zero using laser cooling techniques, but have never actually reached it — the third law of thermodynamics indicates it is impossible to reach absolute zero in a finite number of steps.