Editing Ton (section)

==Units of mass/weight==
There are several similar units of [[mass]] or volume called the '''ton''':

{| class="wikitable"
!Full name(s)
!Common name
!Quantity{{efn|Conversions are exact unless otherwise stated.}}
!Symbol
!width=400|Notes
|-
|[[long ton]]<ref>{{cite web |url=http://www.msc.navy.mil/msfsc/glossary.htm |title=Definitions, Tonnages and Equivalents |website=Military Sealift Fleet Support Command |access-date=2012-12-12 |url-status=dead |archive-url=https://web.archive.org/web/20130516154654/http://www.msc.navy.mil/msfsc/glossary.htm |archive-date=2013-05-16 }}</ref>
|"ton" (United Kingdom)
|{{convert|2,240|lb|kg|sigfig=11|abbr=on|lk=on}}
|LT
|Used in Ireland and [[Commonwealth of Nations|Commonwealth]] countries that formerly used, or still use the [[Imperial unit|Imperial system]]
|-
|[[short ton]]<ref>{{cite web|url=http://ts.nist.gov/WeightsAndMeasures/Publications/appxc.cfm |title=General Tables of Units of Measurement |orig-date=November 11, 2000 |date=April 19, 2006 |website=NIST |access-date=2013-07-01 |url-status=dead |archive-url=https://web.archive.org/web/20111210164956/http://ts.nist.gov/weightsandmeasures/publications/appxc.cfm |archive-date=2011-12-10 }}</ref>
|"ton" (United States)
|{{convert|2,000|lb|kg|sigfig=8|abbr=on}}
|tn<ref name=NIST44-C>
{{cite web
  | url         = https://www.nist.gov/system/files/documents/2023/01/30/appc-23-HB44.pdf
  | title       = NIST Handbook 44 Specifications: Handbook 44 – 2023 Appendix C – General Tables of Units of Measurement
  | page        = C-7
  | date        = November 18, 2022
  | access-date  = May 9, 2023
  | quote       = 20 hundredweights = 1 ton
}}</ref> or st<ref>
{{cite web |url=https://dictionary.cambridge.org/dictionary/english/short-ton  |title=Meaning of short ton in English |website=Cambridge Dictionary |access-date=May 26, 2023}}</ref> 
|Used in the United States and in some industries in Canada
|-
|[[tonne]]<ref name="si2019">{{SIbrochure9th}}</ref><br>(equivalent to one [[megagram]])
|"tonne";<br>"metric ton"
|1,000&nbsp;kg (about 2,204.6226&nbsp;lb)
|t<ref name="si2019">{{SIbrochure9th}}</ref> 
| Defined in the [[International System of Units]]. Used worldwide.
|-
|shortweight ton{{refn|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.<ref>Chris Evans, Göran Rydén, ''Baltic iron in the Atlantic world in the eighteenth century'', p.257, Brill 2007 {{ISBN|90-04-16153-8}}</ref>|name=longshortweight|group=lower-alpha}}
|
|2,240&nbsp;lb
|
|rowspan=2|Used in the iron industry in the 17th and 18th centuries.
|-
|longweight ton<ref name="longshortweight" group="lower-alpha"/>
|
|2,400&nbsp;lb{{refn|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 {{nowrap|25 [[Centum weight|cwt]]}} ({{nowrap|2,800 lb}}) compared to the {{nowrap|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.<ref>"Report of the select committee on mines", ''Reports from Committees 1866'', '''vol.9''', pp.134-136, London: House of Commons, 23 July 1866</ref>|name=altlongweight|group=lower-alpha}}
|
|}

{{notelist|}}

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 ({{IPAc-en|ˈ|t|ʌ|n|i}}).<ref name="oedtonne">{{cite OED|tonne}}</ref> In Australia, it is pronounced {{IPAc-en|t|ɒ|n}}.

In Ireland and most members of the Commonwealth of Nations, a ton is defined as {{convert|2,240|lb|kg|5}}.{{efn|The "pound" used in this article is the [[avoirdupois pound]]. Its mass [[International yard and pound|is defined]] as exactly 0.45359237 kg  }}<ref>{{cite web| url = http://www.opsi.gov.uk/acts/acts1985/pdf/ukpga_19850072_en.pdf| title = Weights and Measures Act 1985| access-date = 2010-02-03| date = 1985-10-30| publisher = Her Majesty's Stationery Office| url-status = live| archive-url = https://web.archive.org/web/20091208083258/http://www.opsi.gov.uk/acts/acts1985/pdf/ukpga_19850072_en.pdf| archive-date = 2009-12-08}}</ref>

In the United States and Canada,<ref name=Canada>{{cite web|url=http://laws-lois.justice.gc.ca/eng/acts/W-6/page-10.html#docCont|title=Weights and Measures Act: Canadian units of measure, Schedule II (Section 4)|publisher=Department of Justice|access-date=2011-07-06|url-status=live|archive-url=https://web.archive.org/web/20110811094412/http://laws-lois.justice.gc.ca/eng/acts/W-6/page-10.html#docCont|archive-date=2011-08-11}}</ref> a ton is defined as {{convert|2000|lb|kg|5}}.

===Other units of mass/weight===
*'''[[Deadweight tonnage|Deadweight ton]]''' (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 ({{convert|1,000|kg|lb|0}}) or long tons ({{convert|2,240|lb|kg|0}}). This measurement is also used in the U.S. tonnage of naval ships.
* Increasingly, '''[[tonne]]s''' are being used rather than long tons in measuring the [[Displacement (ship)|displacement of ships]].
*'''Harbour ton''', used in South Africa in the 20th century, was equivalent to ({{convert|2,000|lb|kg|0}}) or 1 short ton.

{{anchor|Assay ton}}
'''Assay ton''' (abbreviation 'AT') is not a unit of measurement but a standard quantity used in [[assay]]ing ores of precious metals. A '''short assay ton''' is approximately {{convert|29.16666|g|abbr=on|adj=ri2|3}} and a '''long assay ton''' is approximately {{convert|32.66666|g|abbr=on|adj=ri2|3}}.<ref>{{Cite book |last=Fenna |first=Donald |title=A Dictionary of Weights, Measures, and Units |publisher=Oxford University Press |year=2002 |isbn=9780198605225 |location=Oxford |at=assay ton}}</ref>{{citation needed|reason=though the different US/UK values are attested, the terms "short" and "long" with "assay ton" seem only to be found in Wikipedia/Wiktionary and derivative online convertors|date=August 2023}} These amounts bear the same ratio to a milligram as a short or long ton bears to a [[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|reason=No entry for tonne in SOED|date=June 2018}} but in more recent documents ''tonne'' refers exclusively to the [[metric ton]].

In [[nuclear power plant]]s '''tHM''' and '''MTHM''' mean tonnes of [[heavy metals]], and '''MTU''' means tonnes of [[uranium]]. In the [[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]] production or specific consumption.

{{vanchor|Dry ton|Dry tonne|Wet ton|Wet tonne|text=A '''dry ton''' or '''dry tonne''' has the same mass value, but the material ([[sludge]], slurries, [[compost]], and similar mixtures in which solid material is soaked with or suspended in [[water]]) has been dried to a relatively low, consistent [[moisture]] level ([[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 hundredweight|long]] {{convert|112|lb|kg|order=flip}} or [[short hundredweight]] {{convert|100|lb|kg|order=flip}}, respectively.

Before the 20th century there were several definitions. Prior to the 15th century in England, the ton was 20&nbsp;hundredweight, each of 108&nbsp;lb, giving a ton of {{convert|2160|lb|kg}}.{{Citation needed|date=October 2009}}  In the 19th century in different parts of Britain, definitions of 2,240, or 2,352, or 2,400&nbsp;lb were used, with 2,000&nbsp;lb for explosives; the legal ton was usually 2,240&nbsp;lb.<ref>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".</ref>

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.