Absolute temperature is the temperature of an object on a scale where 0 is taken as absolute zero, or the temperature where there is 0 thermal energy in a sample of matter. The unit of absolute temperature is the Kelvin, which has the same increment per unit as the degree Celsius used in the Celsius temperature scale. Absolute temperature must be found in order to proceed with many temperature-based calculations, such as in the ideal gas law.
Common temperatures in the absolute scale are:
- 0°C (freezing point of water) = 273.15K.
- 25°C (room temperature) = 298.15K.
- 100°C (boiling point of water) = 373.15K.
- 0K (absolute zero) = -273.15°C.
To convert from the Celsius scale into the absolute temperature, you add 273.15 and change °C to K. To get a temperature on the absolute scale to the Celsius scale, subtract 273.15 and change K to °C. This is normally used in the science world.