Kelvin to Celsius Calculator — K to °C Converter
Subtract 273.15 from any Kelvin value to get Celsius. Enter K and get °C instantly, plus a Fahrenheit equivalent and a conversion line chart.
K
°C = K − 273.15
- 1
Kelvin input
373.15 - 2
Subtract absolute-zero offset
373.15 − 273.15 = 100Kelvin and Celsius share the same degree size; only the zero point differs by 273.15.
How does this calculator work?
Subtract 273.15 from the Kelvin value to get Celsius: °C = K − 273.15. The relationship is linear with slope 1. Key landmarks: 0 K = −273.15 °C (absolute zero), 273.15 K = 0 °C (water freezes), 310 K = 36.85 °C (human body), 373.15 K = 100 °C (water boils at sea level).
Formula
How this is calculated
Kelvin and Celsius use identical degree sizes — a difference of 1 K is exactly the same as a difference of 1 °C. The only distinction is the zero point: Celsius places 0 at the freezing point of water (273.15 K), while Kelvin places 0 at absolute zero, the lowest possible temperature. So the conversion is simply a constant subtraction: °C = K − 273.15.
The result is a perfectly linear function with a slope of 1 and an x-intercept at 273.15 K. Every additional kelvin equals exactly one additional Celsius degree, making the graph a diagonal line with gradient 1. The chart shows this relationship for a range centred on your input value.
Because Kelvin is always ≥ 0, the corresponding Celsius value is always ≥ −273.15. Temperatures below −273.15 °C do not physically exist, so this calculator rejects negative Kelvin input.
Frequently asked questions
0 K = −273.15 °C. This is absolute zero — the lowest possible temperature, at which a classical ideal gas would have zero pressure and particles would have minimum thermal motion.
300 K = 300 − 273.15 = 26.85 °C, roughly a warm room-temperature day.
Physical equations such as the ideal gas law (PV = nRT), Planck's radiation law, and the Boltzmann equation require an absolute temperature scale — one where zero really means zero thermal energy. Celsius is offset from absolute zero, so plugging Celsius values directly into these equations gives incorrect results.
Also known as
TG we-Calculate Editorial Team. (2026). Kelvin to Celsius Calculator — K to °C Converter [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/kelvin-to-celsius-calculator
TG we-Calculate Editorial Team. "Kelvin to Celsius Calculator — K to °C Converter." TG we-Calculate. 2026. https://we-calculate.com/calculator/kelvin-to-celsius-calculator.
TG we-Calculate Editorial Team, "Kelvin to Celsius Calculator — K to °C Converter," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/kelvin-to-celsius-calculator
@misc{wecalculate_kelvin_to_celsius_calculator, title = {Kelvin to Celsius Calculator — K to °C Converter}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/kelvin-to-celsius-calculator}}, year = {2026}, note = {TG we-Calculate} }
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