There are three similar units of mass
called the ton
- tonne (SI) or metric ton = 1000 kg (2204 lb). The official symbol is t, but mT and T are also used.
- short ton (or simply ton in casual use in U.S.) = 907.185 kg (2000 lb)
- long ton (or weight ton) = 1016.047 kg (2240 lb), commonly used in the UK and for petroleum products.
The word ton
is derived from the Old English tunne
, and ultimately from the Old French tonne
, and referred originally to a large cask with a capacity
of 252 gallons
, which holds approximately 2016 pounds
. Such a barrel is still called a tun
in British English, but usage is now dying out.
The freight ton or measurement ton is also used as what is technically a measure of volume when measuring ship capacities (tonnage) or freights.
One measurement ton is equal to:
- 40 cubic feet
- 1.48148 cubic yards
- 1,132.67 litres
- 1.13267 cubic metres
The amount of water
displaced by a volume of one measurement ton has a mass similar to the tons of mass listed above, 1,132.7 kg or 2497.1 lb.
The measurement ton is abbreviated as M/T, MT or MTON which can cause it to be confused with the metric ton.
The register ton is also a unit of volume, defined as 100 cubic feet. It is often abbreviated as GRT for gross registered ton.
See 1 E-1 m³ for a comparison with other volumes, also orders of magnitude (volume).