Celsius (°C)
Definition
The Celsius scale (symbol °C) is a temperature scale where 0 °C is defined as 273.15 K and 1 °C represents the same temperature interval as 1 kelvin. Water freezes at approximately 0 °C and boils at approximately 100 °C at standard atmospheric pressure.
History
The Swedish astronomer Anders Celsius proposed his scale in 1742, originally setting 0 at the boiling point of water and 100 at the freezing point. After his death the scale was inverted, most likely by the botanist Carl Linnaeus in 1745, to its modern orientation.
From 1948 the unit was officially renamed degree Celsius, replacing the earlier centigrade, partly because centigrade was already an angular unit in French and Spanish. The scale was tied to the kelvin in 1954 and tracks the 2019 SI redefinition of the kelvin via the Boltzmann constant.
Standard reference
Defined by the BIPM SI Brochure as T(°C) = T(K) − 273.15, where the kelvin is fixed via the Boltzmann constant at 1.380649 × 10⁻²³ J/K.
Common conversions
| 0 °C | = 32 °F |
|---|---|
| = 273.15 K | |
| = 491.67 °R |