The long ton, British unit of mass
The long ton is 2240 pounds, that is 1016.047 kilograms, exactly 1.12 short tons. It exceeds the metric tonne by only 1.6 per cent.
That small gap is the trap itself. The shortfall of the short ton shows in any total; the 1.6 per cent of the long ton settles inside the rounding of a docket and surfaces only at settlement. The Washington naval treaty of 1922 capped capital ships at 35,000 long tons of standard displacement, which is 35,562 metric tonnes: 562 tonnes of allowance the text granted without having to write them down. The odd value itself came out of the sea. Naval architects long counted a long ton as the mass of 35 cubic feet of seawater, so a hull volume in cubic feet divided by 35 gave the displacement directly. The arithmetic holds: 35 cubic feet at 1025 kilograms per cubic meter weigh 1015.9 kg, two hundredths of a per cent from the long ton.
The long ton in other units
| 1 ton UK | 1.01605 t |
| 1 ton UK | 1,016 kg |
| 1 ton UK | 1,016,047 g |
| 1 ton UK | 1,016,046,909 mg |
| 1 ton UK | 2,240 lb |
| 1 ton UK | 35,840 oz |
| 1 ton UK | 32,667 oz t |
| 1 ton UK | 160 st |
| 1 ton UK | 5,080,235 ct |
| 1 ton UK | 1.12 ton US |
| 1 ton UK | 1,016,046,908,800 µg |
| 1 ton UK | 2,032 lb metric |
| 1 ton UK | 87,111 tola |
| 1 ton UK | 270,946 momme |
| 1 ton UK | 270.946 kan |
Frequently asked questions
What does a strength in tons per square inch mean?
It is the unit of British drawing offices before metrication: one long ton-force per square inch is 15.444 megapascals, so a steel quoted at 26 tons per square inch stands at 402 megapascals. Old drawings keep that scale, and reading it as short tons would lose eleven per cent of the strength.
Is the long ton still in use?
Not in British trade: since 1 October 1995, goods sold by weight in the United Kingdom are weighed in metric units. It survives elsewhere, notably in the displacement of American warships, still published in long tons, and in North American iron ore and steel, where the gross ton remains the ton of the contract.
Are all a ship's tons weights?
No, and two of them measure nothing but space. The register ton was 100 cubic feet of enclosed volume, that is 2.832 cubic meters, until the 1969 convention replaced it with a dimensionless figure. The freight ton, or measurement ton, is 40 cubic feet, 1.133 cubic meters, and still bills break-bulk cargo whenever volume costs more than mass.