Long, Short, & Metric Tons:
The British Long Ton
is 2,240 pounds (1,016.05 kg).
The U.S. Short Ton
is 2,000 pounds (907.18 kg).
Both tons are actually defined in the same way. One ton is equal to 20 hundredweight. In the U.S. there are 100 pounds in the hundredweight (20 x 100 = 2,000#), and in Britain there are 112 pounds in the hundredweight (20 x 112 = 2,240#).
The Long Ton is used for petroleum products, and for things such as the deadweight tonnage of naval ships. As a displacement
ton, the long ton is normally measured as the mass of 35 cubic feet of sea water* (35 x 64# = 2,240#). Increasingly, metric tons are being used rather than long tons in measuring the displacement
*The density of sea water is about 64 lbs/Ft3
The Metric Ton
(Tonne) is equal to 1000 kilograms, or approximately 2,204.62 pounds (1kg = 2.20462Lbs). The SI standard calls it tonne or megagram (Mg), but the U.S. Government
recommends calling it metric ton.
is a measure of the size or cargo capacity of a ship. Historically, tonnage was the tax on tuns (casks) of wine shipped to England
~ Displacement Tonnage is the actual weight of the vessel and its contents.
~ Deadweight Tonnage is the maximum weight that a ship can safely carry when fully loaded.
~ Gross Tonnage or Gross Register Tonnage is the internal volume of a vessel.
~ Net Tonnage or Net Register Tonnage is Gross Tonnage less the volume of spaces that will not hold cargo.