Litre
The litre (or liter) is an SI derived unit of volume. It is equal to:
- 0.001 cubic metres,
- the volume of a cube of side 10 centimetres
- 1 cubic decimetre
There are 1,000 litres in a cubic metre. See 1 E-3 m³ for a comparison of volumes.
A kilogram of pure water at a temperature of 4 degrees Celsius and standard atmospheric pressure occupies approximately 1 litre of volume.
In the past, this was used to define the kilogram, but not anymore, partially because the volume depends ever-so-slightly on the pressure, and pressure units include mass as a factor, introducing a circular dependency in the definition of the kilogram.