# Ton

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Unit of mass or volume with different values

See also: [Ton of refrigeration](/source/Ton_of_refrigeration)

This article is about the units of measurement. For other uses, see [Ton (disambiguation)](/source/Ton_(disambiguation)).

"A ton" redirects here; not to be confused with [Aton](/source/Aton_(disambiguation)).

Ton General information Unit system British imperial US customary metric Unit of Mass Definitions and equivalents: ton, long ton ton, short ton tonne, metric ton 2,240 lb ~1,016.047 kg 2,000 lb ~907.185 kg 1,000 kg ~2,204.623 lb

A **ton** is any of several [units of measure](/source/Unit_of_measurement) of mass, volume or [force](/source/Ton-force). It has a long history and has acquired several meanings and uses.

As a [unit of mass](/source/Unit_of_mass), *ton* can mean:

- the *[long ton](/source/Long_ton)*, which is 2,240 [pounds](/source/Pound_(mass)) (1,016.0 [kilograms](/source/Kilogram))

- the *[tonne](/source/Tonne)*, also called the *metric ton*, which is 1,000 kilograms (about 2,204.6 pounds) or 1 [megagram](/source/Megagram).

- the *[short ton](/source/Short_ton)*, which is 2,000 pounds (907.2 kilograms)

Its original use as a [unit of volume](/source/Unit_of_volume) has continued in the capacity of cargo ships and in units such as the *[freight ton](/source/Freight_ton)* and a number of other units, ranging from 35 to 100 [cubic feet](/source/Cubic_foot) (0.99 to 2.83 [m3](/source/Cubic_metre)) in size.

Because the ton (of any system of measuring weight) is usually the heaviest unit named in [colloquial](/source/Colloquialism) 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."

## History

The ton is derived from the *[tun](/source/Tun_(volume))*, the term applied to a cask of the largest capacity. This could contain a volume between 175 and 213 [imperial gallons](/source/Imperial_gallon) (210 and 256 [US gal](/source/US_gallon); 800 and 970 [L](/source/Litre)), which could weigh around 2,000 [pounds](/source/Pound_(mass)) (910 [kg](/source/Kilogram)), and occupy some 60 [cubic feet](/source/Cubic_foot) (1.7 [m3](/source/Cubic_metre)) of cargo space.[1]

## Units of mass/weight

There are several similar units of [mass](/source/Mass) or volume called the **ton**:

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 and Commonwealth countries that formerly used, or still use the Imperial 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 one megagram) "tonne"; "metric ton" 1,000 kg (about 2,204.6226 lb) t[6] Defined in the International 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]

1. **[^](#cite_ref-2)** Conversions are exact unless otherwise stated.

1. ^ [***a***](#cite_ref-longshortweight_9-0) [***b***](#cite_ref-longshortweight_9-1) The longweight and shortweight tons were used as a means of making an allowance for wastage in an industrial process. The workman is provided with a longweight ton and is expected to return a shortweight ton of processed product. These measures were particularly used in the operation of hammering iron blooms into shape.[7]

1. **[^](#cite_ref-altlongweight_11-0)** In other industries, a different longweight ton might be used. Coal miners delivered coal to the surface in longweight tons, but were paid only for a shortweight ton. This was supposedly to allow for "dirt" (non-coal rocks) in the output. Mine owners, however, were free to set the value of the longweight ton at a value of their own choosing, and in at least some cases, it was set to 25 [cwt](/source/Centum_weight) (2,800 lb) compared to the 20 cwt shortweight ton. This was a source of discontent amongst the miners who saw the practice as unfair in favour of the mine owners.[8]

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/](https://en.wikipedia.org/wiki/Help:IPA/English)).[9] In Australia, it is pronounced [/tɒn/](https://en.wikipedia.org/wiki/Help:IPA/English).

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).

### Other units of mass/weight

- **[Deadweight ton](/source/Deadweight_tonnage)** (abbreviation 'DWT' or 'dwt') is a measure of a ship's carrying capacity, including bunker oil, fresh water, ballast water, crew, and provisions. It is expressed in tonnes (1,000 kilograms (2,205 lb)) or long tons (2,240 pounds (1,016 kg)). This measurement is also used in the U.S. tonnage of naval ships.

- Increasingly, **[tonnes](/source/Tonne)** are being used rather than long tons in measuring the [displacement of ships](/source/Displacement_(ship)).[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

- **Harbour ton**, used in South Africa in the 20th century, was equivalent to (2,000 pounds (907 kg)) or 1 short ton.

**Assay ton** (abbreviation 'AT') is not a unit of measurement but a standard quantity used in [assaying](/source/Assay) ores of precious metals. A **short assay ton** is approximately 29.17 g (1.029 oz) and a **long assay ton** is approximately 32.67 g (1.152 oz).[12][*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] These amounts bear the same ratio to a milligram as a short or long ton bears to a [troy ounce](/source/Troy_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 word *ton* is sometimes spelled *tonne*,[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] but in more recent documents *tonne* refers exclusively to the [metric ton](/source/Metric_ton).

In [nuclear power plants](/source/Nuclear_power_plant) **tHM** and **MTHM** mean tonnes of [heavy metals](/source/Heavy_metals), and **MTU** means tonnes of [uranium](/source/Uranium). In the [steel](/source/Steel) industry, the abbreviation **THM** means 'tons/tonnes hot metal', which refers to the amount of liquid iron or steel that is produced, particularly in the context of [blast furnace](/source/Blast_furnace) production or specific consumption.

A **dry ton** or **dry tonne** has the same mass value, but the material ([sludge](/source/Sludge), slurries, [compost](/source/Compost), and similar mixtures in which solid material is soaked with or suspended in [water](/source/Water)) has been dried to a relatively low, consistent [moisture](/source/Moisture) level ([dry weight](/source/Dry_weight)). If the material is in its natural, wet state, it is called a **wet ton** or **wet tonne**.

### Subdivisions

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 are [long](/source/Long_hundredweight) 112 pounds (51 kg) and [short](/source/Short_hundredweight) 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](https://en.wikipedia.org/wiki/Wikipedia: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.

## Units of volume

See also: [Tonnage](/source/Tonnage)

The [displacement](/source/Displacement_(ship)), essentially the weight, of a ship is traditionally expressed in [long tons](/source/Long_ton).[14] To simplify measurement it is determined by measuring the [volume](/source/Volume), rather than weight, of water displaced, and calculating the weight from the volume and density.[15] For practical purposes the **displacement ton** (DT) is a unit of volume, 35 cubic feet (0.9911 m3), the approximate volume occupied by one ton of [seawater](/source/Seawater) (the actual volume varies with salinity and temperature).[16] It is slightly less than the 224 imperial gallons (1.018 m3) of the **water ton** (based on [distilled water](/source/Distilled_water)).

One **[measurement ton](/source/Shipping_ton)** or **freight 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](/source/Gross_tonnage)** and **[net tonnage](/source/Net_tonnage)** are volumetric measures of the cargo-carrying capacity of a ship.

The **Panama Canal/Universal Measurement System (PC/UMS)** is based on [net tonnage](/source/Net_tonnage), modified for Panama Canal billing purposes. PC/UMS is based on a mathematical formula to calculate a vessel's total volume; a **PC/UMS net ton** is equivalent to 100 cubic feet of capacity.[21]

The **water 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 the [imperial](/source/Imperial_units) [gallon](/source/Gallon).

## Colloquial English

- **Ton** is also used informally, often as [slang](/source/Slang), to mean a large amount of something.[23]

- In [Britain](/source/United_Kingdom), a ton is colloquially used to refer to 100 of a given unit. Ton can thus refer to a speed of 100 miles per hour (160 km/h), and is prefixed by an indefinite article, e.g. "Lee was doing a ton down the motorway"; to money e.g. "How much did you pay for that?" "A ton" (£100); to 100 points in a game e.g. "Eric just threw a ton in our darts game" (in some games, e.g. [cricket](/source/Cricket), more commonly called a century); or to a hundred of any other countable figure.[24][25][26]

## See also

Look up ***[ton](https://en.wiktionary.org/wiki/ton)*** in Wiktionary, the free dictionary.

- [Conversion of units](/source/Conversion_of_units)

- [English units](/source/English_units_of_measurement)

- [Gross ton mile](/source/Gross_ton_mile)

- [Imperial units](/source/Imperial_units)

- [Systems of measurement](/source/Systems_of_measurement)

- [TNT equivalent](/source/TNT_equivalent)

- [Ton of refrigeration](/source/Ton_of_refrigeration)

- [truck classification](/source/Truck_classification)

- unit of [energy](/source/Energy)

- [United States customary units](/source/United_States_customary_units)

## References

1. **[^](#cite_ref-13)** The "pound" used in this article is the [avoirdupois pound](/source/Avoirdupois_pound). Its mass [is defined](/source/International_yard_and_pound) as exactly 0.45359237 kg

1. **[^](#cite_ref-BTS.GOV_1-0)** ["Naval Architecture for All"](https://web.archive.org/web/20081010071508/http://ntl.bts.gov/DOCS/narmain/narmain.html). United States Bureau of Transportation Statistics. Archived from [the original](http://ntl.bts.gov/DOCS/narmain/narmain.html) on October 10, 2008. Retrieved October 13, 2008.. "Historically, a very important and standard cargo for European sailing vessels was wine, stored and shipped in casks called tuns. These tuns of wine, because of their uniform size and their universal demand, became a standard by which a ship's capacity could be measured. A tun of wine weighed approximately 2,240 pounds, and occupied nearly 60 cubic feet." ([Gillmer, Thomas](/source/Thomas_C._Gillmer) (1975). *Modern Ship Design*. United States Naval Institute.) "Today the ship designers standard of weight is the long ton which is equal to 2,240 pounds." This is the weight of 35 cubic feet of Sea Water at a specific gravity of 1.025, compared to Fresh Water, specific gravity of 1.000 usually measured at 60 degrees F. Handy numbers: 35, 36, 37, number of Cubic Feet per Salt Water, Fresh Water and Lube Oil.

1. **[^](#cite_ref-3)** ["Definitions, Tonnages and Equivalents"](https://web.archive.org/web/20130516154654/http://www.msc.navy.mil/msfsc/glossary.htm). *Military Sealift Fleet Support Command*. Archived from [the original](http://www.msc.navy.mil/msfsc/glossary.htm) on 2013-05-16. Retrieved 2012-12-12.

1. **[^](#cite_ref-4)** ["General Tables of Units of Measurement"](https://web.archive.org/web/20111210164956/http://ts.nist.gov/weightsandmeasures/publications/appxc.cfm). *NIST*. April 19, 2006 [November 11, 2000]. Archived from [the original](http://ts.nist.gov/WeightsAndMeasures/Publications/appxc.cfm) on 2011-12-10. Retrieved 2013-07-01.

1. **[^](#cite_ref-NIST44-C_5-0)** ["NIST Handbook 44 Specifications: Handbook 44 – 2023 Appendix C – General Tables of Units of Measurement"](https://www.nist.gov/system/files/documents/2023/01/30/appc-23-HB44.pdf) (PDF). November 18, 2022. p. C-7. Retrieved May 9, 2023. 20 hundredweights = 1 ton

1. **[^](#cite_ref-6)** ["Meaning of short ton in English"](https://dictionary.cambridge.org/dictionary/english/short-ton). *Cambridge Dictionary*. Retrieved May 26, 2023.

1. ^ [***a***](#cite_ref-si2019_7-0) [***b***](#cite_ref-si2019_7-1) [*The International System of Units*](https://www.bipm.org/documents/20126/41483022/SI-Brochure-9-EN.pdf) (PDF), V4.01 (9th ed.), International Bureau of Weights and Measures, Jun 2026, [ISBN](/source/ISBN_(identifier)) [978-92-822-2272-0](https://en.wikipedia.org/wiki/Special:BookSources/978-92-822-2272-0)

1. **[^](#cite_ref-8)** Chris Evans, Göran Rydén, *Baltic iron in the Atlantic world in the eighteenth century*, p.257, Brill 2007 [ISBN](/source/ISBN_(identifier)) [90-04-16153-8](https://en.wikipedia.org/wiki/Special:BookSources/90-04-16153-8)

1. **[^](#cite_ref-10)** "Report of the select committee on mines", *Reports from Committees 1866*, **vol.9**, pp.134-136, London: House of Commons, 23 July 1866

1. **[^](#cite_ref-oedtonne_12-0)** ["tonne"](https://www.oed.com/search/dictionary/?q=tonne). *[Oxford English Dictionary](/source/Oxford_English_Dictionary)* (online ed.). Oxford University Press. (Subscription or [participating institution membership](https://www.oed.com/public/login/loggingin#withyourlibrary) required.)

1. **[^](#cite_ref-14)** ["Weights and Measures Act 1985"](http://www.opsi.gov.uk/acts/acts1985/pdf/ukpga_19850072_en.pdf) (PDF). Her Majesty's Stationery Office. 1985-10-30. [Archived](https://web.archive.org/web/20091208083258/http://www.opsi.gov.uk/acts/acts1985/pdf/ukpga_19850072_en.pdf) (PDF) from the original on 2009-12-08. Retrieved 2010-02-03.

1. **[^](#cite_ref-Canada_15-0)** ["Weights and Measures Act: Canadian units of measure, Schedule II (Section 4)"](https://laws-lois.justice.gc.ca/eng/acts/W-6/page-10.html#docCont). Department of Justice. [Archived](https://web.archive.org/web/20110811094412/http://laws-lois.justice.gc.ca/eng/acts/W-6/page-10.html#docCont) from the original on 2011-08-11. Retrieved 2011-07-06.

1. **[^](#cite_ref-16)** Fenna, Donald (2002). *A Dictionary of Weights, Measures, and Units*. Oxford: Oxford University Press. assay ton. [ISBN](/source/ISBN_(identifier)) [9780198605225](https://en.wikipedia.org/wiki/Special:BookSources/9780198605225).

1. **[^](#cite_ref-17)** Definitions of 2,000, 2,240, 2,352, and 2,400 lb are included in citations listed in the Oxford English Dictionary, 2nd ed. OED cites an 1858 dictionary of trade products "the legal ton by weight is usually 20 cwt".

1. **[^](#cite_ref-18)** DesVergers, Jake. ["Rules of the Road: Tricky tonnage measurement not about weight"](https://www.the-triton.com/2017/10/rules-of-the-road-tricky-tonnage-measurement-not-about-weight/). *The Triton*. Retrieved 2021-04-23.

1. **[^](#cite_ref-19)** [Displacement ton](https://books.google.com/books?id=vylCkqTg7H0C&pg=PA249) Dictionary of international trade retrieved 22July2010

1. **[^](#cite_ref-20)** [A Dictionary of Weights, Measures, and Units, Donald Fenna, 2002](http://www.oxfordreference.com/views/ENTRY.html?entry=t135.e351&srn=1&ssid=351170645#FIRSTHIT) [ISBN](/source/ISBN_(identifier)) [0-19-860522-6](https://en.wikipedia.org/wiki/Special:BookSources/0-19-860522-6)

1. **[^](#cite_ref-21)** ["MSC 2003 in Review - Financial and Statistical Review"](https://web.archive.org/web/20110722195701/http://www.msc.navy.mil/annualreport/2003/financial.htm). Msc.navy.mil. 2003-09-30. Archived from [the original](http://www.msc.navy.mil/annualreport/2003/financial.htm) on 2011-07-22. Retrieved 2010-07-31.

1. **[^](#cite_ref-22)** ["Liner Ocean Transportation Program Stabilized Breakbulk/Dry Cargo and Container Billing Rates"](https://www.ustranscom.mil/dbw/docs/FY18_Liner_Breakbulk_and_Container_Rates_and_Guidance.pdf) (PDF). Military Surface Deployment and Distribution Command. 2018.

1. **[^](#cite_ref-23)** ["182 F.2d 916"](https://web.archive.org/web/20110727214911/http://bulk.resource.org/courts.gov/c/F2/182/182.F2d.916.235.21638.html). Bulk.resource.org. Archived from [the original](http://bulk.resource.org/courts.gov/c/F2/182/182.F2d.916.235.21638.html) on 2011-07-27. Retrieved 2010-07-31.

1. **[^](#cite_ref-24)** ["Pos Ttariff General Definitions"](http://www.stocktonport.com/TERMINAL%20TARIFF/POS%20DEFINITIONS%20GENERAL%20RULES%20AND%20REGULATIONS%20ttariffI.htm). Stocktonport.com. [Archived](https://web.archive.org/web/20110716144906/http://www.stocktonport.com/TERMINAL%20TARIFF/POS%20DEFINITIONS%20GENERAL%20RULES%20AND%20REGULATIONS%20ttariffI.htm) from the original on 2011-07-16. Retrieved 2010-07-31.

1. **[^](#cite_ref-25)** [*Panama Canal Tolls*](http://www.pancanal.com/eng/general/peajes-en-el-canal.html) [Archived](https://web.archive.org/web/20080916113752/http://www.pancanal.com/eng/general/peajes-en-el-canal.html) 2008-09-16 at the [Wayback Machine](/source/Wayback_Machine), [Panama Canal Authority](/source/Panama_Canal_Authority). Retrieved 10 May 2006.

1. **[^](#cite_ref-26)** ["NIST: Units and Systems of Measurement Their Origin, Development, and Present Status"](https://www.nist.gov/pml/wmd/pubs/upload/AppB-12-hb44-final.docx). *nist.gov*. [Archived](https://web.archive.org/web/20160616205300/http://www.nist.gov/pml/wmd/pubs/upload/AppB-12-hb44-final.docx) from the original on 16 June 2016. Retrieved 1 May 2018.

1. **[^](#cite_ref-27)** Merriam-Webster's English Dictionary defines ton as: "a great quantity". [\[1\]](https://www.merriam-webster.com/dictionary/ton)

1. **[^](#cite_ref-28)** Colin R. Chapman, *Weights, Money and Other Measures Used by our Ancestors*, p.93, Genealogical Publishing Com, 1996 [ISBN](/source/ISBN_(identifier)) [0-8063-1501-6](https://en.wikipedia.org/wiki/Special:BookSources/0-8063-1501-6).

1. **[^](#cite_ref-29)** MacRae-Hall, John (2011). [*A Deniable Asset*](https://books.google.com/books?id=_MaEhEXt2W8C&pg=PA85). iUniverse. p. 85. [ISBN](/source/ISBN_(identifier)) [9781450280808](https://en.wikipedia.org/wiki/Special:BookSources/9781450280808).

1. **[^](#cite_ref-30)** The Oxford English Dictionary 2nd ed. lists colloquial use of "ton" from 1946 for £100, and later 100 mph, and for 100 in general.

v t e Imperial units Comparison with US customary system Length Twip Thousandth of an inch Barleycorn Inch Hand Link Foot Yard Fathom Rod Chain Furlong Cable Mile Nautical mile League Area Square inch Square foot Square yard Perch Rood Acre Square mile Volume Derived Cubic inch Cubic foot Hoppus Cubic yard Cubic mile Tmcft Cooking Teaspoon Tablespoon Fluid ounce Cup Pint Quart Trade gallon Gallon Other Chaldron Minim Gill Fluid Scruple Fluid Drachm Peck Bushel Barrel Stuck Hogshead Speed Miles per hour Mass Grain Drachm Ounce Pound (mass) Stone Quarter Slug Long hundred Hundredweight Ship load Ton Pressure Ksi Pounds per square inch Other units and measures British thermal unit Degree Fahrenheit Rankine Foot-candle Foot-pound Foot-poundal Horsepower Horsepower-hour Kenning Pound (force) Pound-foot Poundal Span Related systems Avoirdupois system English units Winchester Exchequer English Engineering units Foot–pound–second system (FPS) Twenty-foot equivalent unit

v t e United States customary units Comparison with imperial unit system Length Thousandth of an inch Inch Hand Link Foot Yard Rod Chain Furlong Mile Statute mile Area Square inch Square foot Square yard Acre Square mile Volume Derived Cubic inch Cubic foot Cubic yard Cubic mile Cooking Teaspoon Tablespoon Fluid ounce Cup Pint Quart Gallon Wood Board foot Cord Face cord Other Minim Gill Peck Bushel Barrel Acre-foot Speed Foot per second Miles per hour Mass Grain Dram Ounce Pound Hundredweight Ton Long Short Force Poundal Pound-force Kip Pressure Inch of mercury Pound per square inch Kilopound per square inch Other units and measures Bolt (cloth) British thermal unit Degree (angle) Fahrenheit Foot-candle Foot-lambert Foot-pound (energy) Horsepower Perm Pound-foot (torque) Ton of refrigeration Related systems American wire gauge Avoirdupois system Body jewelry sizes English Engineering Units Foot–pound–second system of units

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