The official SI unit is the megagram (Mg), a less common way to express the same amount.

Ton and tonne are both derived from a Germanic word in general use in the North Sea area since the Middle Ages (cf.

[8] A full tun, standing about a metre high, could easily weigh a tonne.

See also the common German word de:Mülltonne (literal translation: garbage drum).

The spelling tonne pre-dates the introduction of the SI in 1960; it has been used with this meaning in France since 1842,[9] when there were no metric prefixes for multiples of 106 and above, and is now used as the standard spelling for the metric mass measurement in most English-speaking countries.

Kilotonne, megatonne, and gigatonne are more usually used for the energy of nuclear explosions and other events in equivalent mass of TNT, often loosely as approximate figures.

[20][21] The following excerpt from a mining geology textbook describes its usage in the particular case of tungsten:

In the petroleum industry, the tonne of oil equivalent (toe) is a unit of energy: the amount of energy released by burning one tonne of crude oil, approximately 42 GJ.

Like the gram and the kilogram, the tonne gave rise to a (now obsolete) force unit of the same name, the tonne-force, equivalent to about 9.8 kilonewtons.