There are three similar units of mass called the ton or tonne:
- 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 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 register ton is also a unit of volume, defined as 100 cubic feet. It is often abbreviated as GRT for gross registered ton.