Room for ChanceWhat it measures and where it is used
Temperature describes thermal state and is used in weather, cooking and science. Celsius and Fahrenheit have different zero points and step sizes. Kelvin is the SI unit of thermodynamic temperature, defined through the Boltzmann constant since 2019. This tool converts temperatures, not temperature intervals.
- Classification
- SI base quantity
- SI unit
- K
- Dimension
- Θ
L: length; M: mass; T: time; Θ: temperature; N: amount of substance. The dimension symbol N is not the unit symbol for newton.
How it works
Temperature needs an offset as well as a scale factor: °F = °C × 9/5 + 32 and K = °C + 273.15. Absolute temperatures below 0 K are rejected. Temperature differences require a different calculation.
Example
0 °C ≈ 32 °F
Available units
Reference unit: K
| Available units | Reference factor |
|---|---|
| °C | 1 × x + 273.15 |
| °F | 0.555555555556 × x + 255.372222222 |
| K | 1 × x + 0 |
| °R | 0.555555555556 × x + 0 |
Units, history and conventions
The International System of Units (SI) received its name in 1960. Since the 2019 revision, its definitions use fixed values of seven defining constants. SI base and derived quantities should not be confused with the different units used to express them.
IUPAC does not replace the SI: its Green Book standardises quantities, symbols and terminology in physical chemistry. Its predecessor was published in 1969. The mole is particularly important when counting specified chemical entities.