The ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight. Its original use as a measurement of volume has continued in the capacity of cargo ships and in terms such as the freight ton. Recent specialized uses include the ton as a measure of energy and for truck classification. It is also a colloquial term, "ton" (any definition) is the heaviest unit of weight typically used in colloquial speech. It is also used informally to mean a large amount of something, material or not.
|1 t in ...||... is equal to ...|
|SI derived unit||1016.0469 kg (long)|
|SI derived unit||907.18474 kg (short)|
Where confusion is possible, the 2240 lb ton is called "long ton" and the 2000 lb ton "short ton". The 1000 kg tonne is distinguished by its spelling, but usually pronounced the same as ton, hence the US term "metric ton". In the UK the final "e" of "tonne" can also be pronounced (//), or "metric ton" when it is necessary to make the distinction.
Where precision is required the correct term must be used, but for many purposes this is not necessary: the metric and long tons differ by only 1.6%.
The term "ton" is also used to refer to a number of units of volume, ranging from 35 to 100 cubic feet (0.99 to 2.83 m3) in capacity. It can also be used as a unit of energy, or in refrigeration as a unit of power, sometimes called a ton of refrigeration.