Long ton
The long ton is a British unit of mass equal to 2,240 avoirdupois pounds, or 1,016.0469 kilograms. It is also called the imperial ton.
Avoirdupois system: A system of weights based on the avoirdupois pound of 16 ounces, used for most everyday goods in English-speaking countries. The long ton is defined as 2,240 pounds in this system.
Imperial units: A system of weights and measures established in Britain in 1824 and later used across the British Empire. The long ton belongs to the British system of imperial mass units.
Displacement (ship): The weight of water displaced by a vessel, used to express the vessel’s mass. Older ship specifications commonly express displacement in long tons.
Ton-force: A unit of force equal to the weight of one ton under standard gravity; its value depends on which ton is specified. A long ton measures mass, while ton-force measures force.
Pound (mass): A unit of mass equal to 16 avoirdupois ounces, or exactly 0.45359237 kilograms. Multiplying this pound by 2,240 gives the long ton.
Weights and Measures Act 1824: A British act that established the imperial system of weights and measures. The act formalized the measurement system in which the long ton became standard.
Deadweight tonnage: A measure of a ship’s carrying capacity, expressed as the mass of cargo, fuel, stores, and other loads it can carry. Historical and some British records state this capacity in long tons.
Tonne-force: A non-SI unit of force equal to the weight of one metric tonne under standard gravity. Its name resembles the long ton, but it denotes force rather than mass.
Metric tonne: A unit of mass equal to exactly 1,000 kilograms, also called a tonne. Its round metric value distinguishes it from the heavier long ton.
British Weights and Measures Acts: A series of British laws regulating measurement standards, units, and trade practices. Later legislation maintained and refined the long ton’s legal context.