# Long ton

Long ton
Unit systemImperial units, U.S. customary units
Unit ofMass
In base units2,240 lb
Conversions
1 in ...... is equal to ...
SI base units   1,016.047 kg
Metric tons   1.016047 t
Short tons   1.12 short tons (exactly)

Long ton,[1] also known as the imperial ton or displacement ton,[1][2] is the name for the unit called the "ton" in the avoirdupois system of weights or Imperial system of measurements. It was standardised in the thirteenth century and is used in the United Kingdom and several other British Commonwealth of Nations countries alongside the mass-based metric tonne defined in 1799.

It is not to be confused with the short ton a unit of weight equal to 2,000 pounds (907.18474 kg) used in the United States, and in Canada before metrication, also referred to simply as a "ton".

## Unit definition

A long ton is defined as exactly 2,240 pounds. The long ton arises from the traditional British measurement system: A long ton is 20 hundredweight (cwt), each of which is 8 stone (1 stone = 14 pounds). Thus a long ton is 20 × 8 × 14 lb = 2,240 lb.

## Unit equivalences

A long ton, also called the weight ton (W/T),[1] imperial ton, or displacement ton, is equal to:

• 2,240 pounds or 1,016 kilograms or 1.016 metric tons
• 12% more than the 2,000 pounds of the North American short ton
• the weight of 35 cubic feet (0.99 m3) of salt water with a density of 64 pounds per cubic foot (1.03 g/cm3)[1]

It has some limited use in the United States, most commonly in measuring the displacement of ships, the volume-to-carrying-weight of fuels and in trade of baled commodities[1] and bulk goods like elemental sulfur. The long ton was the unit prescribed for warships by the Washington Naval Treaty of 1922—for example battleships were limited to a displacement of 35,000 long tons (36,000 t; 39,000 short tons).

To comply with the practices of the European Union, the British Imperial ton was explicitly excluded from use for trade by the United Kingdom's Weights and Measures Act of 1985.[3][4]