A tonne (also called metric tonne) is a non-SI unit of mass, accepted for use with SI, defined as:

1 tonne = 10³ kg (= 10⁶ g).

It is approximately equal to 2,204.62262 pounds.

The naming of this unit was far from original because SI advocates derived the name of their unit from the already well established ton and added an '-ne' suffix to differentiate between the SI tonne and non-metric ton. The tonne is also less formally called metric ton but this name is deprecated since it mixes metric and non-metric terms.

The official symbol is t, but mT and T are also used.

The tonne may also be referred to by the strictly SI term megagram, symbol Mg.

kilogram « tonne/megagram « gigagram