A cubic metre of pure water at the temperature of maximum density (3.98 °C) and standard atmospheric pressure (101.325 kPa) has a mass of , or one tonne. At 0 °C, the freezing point of water, a cubic metre of water has slightly less mass, 999.972 kilograms.
It is sometimes abbreviated to cu m, m3, M3, m^3, m**3, CBM, cbm when superscriptcharacters or markup cannot be used (e.g. in some typewritten documents and postings in Usenet newsgroups). The "cubic metre" symbol is encoded by Unicode at code point ㎥SQUARE M CUBED ? m^3 ?.
Multiples and submultiples
the volume of a cube of side length one decametre (10 m)
^From 1901 to 1964 the litre was defined as the volume of one kilogram of pure water at 4°C and 760 millimetres of mercury pressure. During this time, a litre was about . In 1964 the original definition was reverted to.
^The cubic centimetre is the base unit of volume of the CGS system of units. The colloquial abbreviations "cc"/"cc" and "ccm" are not SI but are common in some contexts such as cooking, engine displacement and medicine.