A cubic metre of pure water at the temperature of maximum density (3.98 °C or 39.16 °F) and standard atmospheric pressure (101.325 kPa) has a mass of 1000kg, 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).
Abbreviated CBM and cbm in the freight business and MTQ (or numeric code 49) in international trade.
^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 1.000028 dm3. 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" and "ccm" are not SI but are common in some contexts such as cooking, engine displacement and medicine.