Megagram

A tonne (t) or metric ton (M/T), also referred to as a metric tonne, is a measurement of mass equal to 1,000 kilograms. It is not an SI unit but is accepted for use with the SI. The proper SI unit for a tonne would be a "megagram" (Mg, see SI prefix), but this term is rarely used in practice. Though the spelling tonne predates the introduction of the SI system in 1960, it is now used as the standard spelling for the metric mass measurement in English. The similar Imperial units and United States customary units are spelled ton in English.
See more at Wikipedia.org...