Metric ton/Legends
A metric ton was a unit used to measure large quantities of mass, such as the cargo capacity of spaceships. Gigatons, kilotons, and megatons[1] were terms for larger numbers of metric tons, and were often used to describe the destructive power of weapons.
Behind the scenes
The roleplaying games by West End Games (D6) and Wizards of the Coast (d20 & Saga) included measurements in metric tons for the cargo capacity of large vehicles such as tramp freighters.