| Ton | |
|---|---|
 | |
| General information | |
| Unit system | |
| Unit of | Mass |
| Conversions | |
| 1 in ... | ... is equal to ... |
| kilograms | 1,016.0469 kg (ton, long ton) |
| 907.1847 kg (ton, short ton) | |
| 1,000 kg (tonne, metric ton) | |
| pounds | 2,240 lb (ton, long ton) |
| 2,000 lb (ton, short ton) | |
| 2,204.62 lb (tonne, metric ton) | |
Ton is any of severalunits of measure of mass, volume orforce. It has a long history and has acquired several meanings and uses.
As aunit of mass,ton can mean:
Its original use as aunit of volume has continued in the capacity of cargo ships and in units such as thefreight ton and a number of other units, ranging from 35 to 100cubic feet (0.99 to 2.83 m3) in size.
Because the ton (of any system of measuring weight) is usually the heaviest unit named incolloquial speech, its name also has figurative uses, singular and plural, informally meaning a large amount or quantity, or to a great degree, as in "There's a ton of bees in this hive," "We have tons of homework," and "I love you a ton."
The ton is derived from thetun, the term applied to a cask of the largest capacity. This could contain a volume between 175 and 213imperial gallons (210 and 256 US gal; 800 and 970 L), which could weigh around 2,000pounds (910 kg), and occupy some 60cubic feet (1.7 m3) of cargo space.[1]
There are several similar units ofmass or volume called theton:
| Full name(s) | Common name | Quantity[a] | Symbol | Notes |
|---|---|---|---|---|
| long ton[2] | "ton" (United Kingdom) | 2,240 lb (1,016.0469088 kg) | LT | Used in Ireland andCommonwealth countries that formerly used, or still use theImperial system |
| short ton[3] | "ton" (United States) | 2,000 lb (907.18474 kg) | tn[4] or st[5] | Used in the United States and in some industries in Canada |
| tonne[6] (equivalent to onemegagram) | "tonne"; "metric ton" | 1,000 kg (about 2,204.6226 lb) | t[6] | Defined in theInternational System of Units. Used worldwide. |
| shortweight ton[b] | 2,240 lb | Used in the iron industry in the 17th and 18th centuries. | ||
| longweight ton[b] | 2,400 lb[c] |
The difference between the short ton and the other common forms ("long" and "metric") is about 10%, while the metric and long tons differ by less than 2%.
The metric tonne is usually distinguished by its spelling when written, but in the United States and United Kingdom, it is pronounced the same as ton, hence is often spoken as "metric ton" when it is necessary to make the distinction. In the United Kingdom the final "e" of "tonne" can also be pronounced (/ˈtʌni/).[9] In Australia, it is pronounced/tɒn/.
In Ireland and most members of the Commonwealth of Nations, a ton is defined as 2,240 pounds (1,016.04691 kg).[a][10]
In the United States and Canada,[11] a ton is defined as 2,000 pounds (907.18474 kg).
Assay ton (abbreviation 'AT') is not a unit of measurement but a standard quantity used inassaying ores of precious metals. Ashort assay ton is approximately 29.17 g (1.029 oz) and along assay ton is approximately 32.67 g (1.152 oz).[12][citation needed] These amounts bear the same ratio to a milligram as a short or long ton bears to atroy ounce. Therefore, the number of milligrams of a particular metal found in a sample weighing one assay ton gives the number of troy ounces of metal contained in a ton of ore.
In documents that predate 1960 the wordton is sometimes spelledtonne,[citation needed] but in more recent documentstonne refers exclusively to themetric ton.
Innuclear power plantstHM andMTHM mean tonnes ofheavy metals, andMTU means tonnes ofuranium. In thesteel industry, the abbreviationTHM means 'tons/tonnes hot metal', which refers to the amount of liquid iron or steel that is produced, particularly in the context ofblast furnace production or specific consumption.
Adry ton ordry tonne has the same mass value, but the material (sludge, slurries,compost, and similar mixtures in which solid material is soaked with or suspended inwater) has been dried to a relatively low, consistentmoisture level (dry weight). If the material is in its natural, wet state, it is called awet ton orwet tonne.
Both the UK definition of long ton and US definition of short ton have similar underlying bases. Each is equivalent to 20 hundredweight; however, they arelong 112 pounds (51 kg) andshort 100 pounds (45 kg) hundredweight, respectively.
Before the 20th century there were several definitions. Prior to the 15th century in England, the ton was 20 hundredweight, each of 108 lb, giving a ton of 2,160 pounds (980 kg).[citation needed] In the 19th century in different parts of Britain, definitions of 2,240, or 2,352, or 2,400 lb were used, with 2,000 lb for explosives; the legal ton was usually 2,240 lb.[13]
In the United Kingdom, Canada, Australia, and other areas that had used the imperial system, the tonne is the form of ton legal in trade.
Thedisplacement, essentially the weight, of a ship is traditionally expressed inlong tons.[14] To simplify measurement it is determined by measuring thevolume, rather than weight, of water displaced, and calculating the weight from the volume and density.[15]For practical purposes thedisplacement ton (DT) is a unit of volume, 35 cubic feet (0.9911 m3), the approximate volume occupied by one ton ofseawater (the actual volume varies with salinity and temperature).[16] It is slightly less than the 224 imperial gallons (1.018 m3) of thewater ton (based ondistilled water).
Onemeasurement ton orfreight ton is equal to 40 cubic feet (1.133 m3), but historically it has had several different definitions. It is used to determine the amount of money to be charged in loading, unloading, or carrying different sorts of cargo. In general if a cargo is heavier than salt water, the actual weight is used. If it is lighter than salt water, e.g. feathers, freight is calculated in measurement tons of 40 cubic feet.[17][18][19][20]
Gross tonnage andnet tonnage are volumetric measures of the cargo-carrying capacity of a ship.
ThePanama Canal/Universal Measurement System (PC/UMS) is based onnet tonnage, modified for Panama Canal billing purposes. PC/UMS is based on a mathematical formula to calculate a vessel's total volume; aPC/UMS net ton is equivalent to 100 cubic feet of capacity.[21]
Thewater ton is used chiefly in Great Britain, in statistics dealing with petroleum products, and is defined as 224 imperial gallons (35.96 cu ft; 1.018 m3),[22] the volume occupied by 1 long ton (2,240 lb; 1,016 kg) of water under the conditions that define theimperialgallon.
20 hundredweights = 1 ton