Cargo Tonnage

Most ocean freight is billed on the basis of weight or measurement tons (W/M). Weight tons can be expressed in short tons of 2000 pounds, long tons of 2240 pounds or metric tons of 1000 kilos (2204.62 pounds). Measurement tons are usually expressed as cargo measurement of 40 cubic feet (1.12 meters) or cubic meters (35.3 cubic feet.)

Source: U.S. Maritime Administration.