Editing Ounce

{{Short description|Unit of mass}}
{{Redirect|oz.|other uses|Ounce (disambiguation)|and|Oz (disambiguation)}}
{{Use dmy dates|date=July 2024}}
{{Infobox unit
| name          = Ounce
| caption       = 
| standard      = [[Imperial system]]
| quantity      = Measurement
| symbol        = ℥
}}
The  '''ounce''' ({{IPAc-en|'|au|n|s}}) is any of several different units of [[mass]], [[weight]], or [[volume]] and is derived almost unchanged from the {{lang|la|uncia}}, an [[Ancient Roman units of measurement|Ancient Roman unit of measurement]].

The [[#International avoirdupois ounce|avoirdupois ounce]] (exactly {{cvt|1|oz|9|disp=out|comma=gaps}}) is {{frac|1|16}} [[Pound (mass)#Avoirdupois pound|avoirdupois pound]]; this is the [[United States customary units|United States customary]] and British [[imperial unit|imperial]] ounce. It is primarily used in the United States.

Although the avoirdupois ounce is the mass measure used for most purposes, the '[[troy ounce]]' of exactly {{cvt|1|ozt|g|7|disp=out|comma=gaps}} is used instead for the mass of [[precious metal]]s such as gold, silver, platinum, palladium, rhodium, etc.

The term 'ounce' is also used in other contexts:
* The [[#Ounce-force|ounce-force]] is a measure of [[force]] (see below).
* The [[fluid ounce]] is a measure of [[volume]].

Historically, a variety of different ounces measuring mass or volume were used in different jurisdictions by different trades and at different times in history.

== Etymology ==
''Ounce'' derives from the Ancient Roman {{lang|la|[[uncia (unit)|uncia]]}} (meaning: a twelfth), a unit in the [[Ancient Roman units of measurement]] weighing about 27.4 grams or 96.7% of an avoirdupois ounce,<ref>{{cite encyclopedia | title=Measurement system |author=Ronald Zupko |url=https://www.britannica.com/science/measurement-system#ref360981 |encyclopedia=Encyclopedia Britannica }}</ref> that was one-twelfth ({{frac|1|12}}) of the [[pound (mass)#Roman libra|Roman pound]] ({{lang|la|libra}}).<ref>{{L&S|uncia|ref}}</ref> This in turn comes from Latin {{lang|la|unus}} ('one'), and thus originally meant simply 'unit'. The term ''uncia'' was borrowed twice: first into Pre–[[Old English]], becoming {{lang|ang|ynce}} in Old English, which survives in modern English as ''[[inch]]'';<ref>{{OED|inch}}</ref> and a second time into [[Middle English]] through [[Anglo-Norman language|Anglo-Norman]] and [[Middle French]] ({{lang|enm|unce, once, ounce}}), yielding English ''ounce''.<ref>{{OED|ounce}}</ref> The abbreviation ''oz'' came later from the Italian [[cognate]] {{lang|it|onza}}, pronounced {{IPA|it|ˈontsa|}} (or later {{lang|it|oncia}}, pronounced {{IPA|it|ˈontʃa|}}).

== Definitions ==
Historically, in different parts of the world, at different points in time, and for different applications, the ounce (or its translation) has referred to broadly similar but still slightly different standards of mass.

{| class="wikitable sortable"
|+ Mass of ounce units
! Variant
! ([[gram]]s)
! ([[grain (measure)|grain]]s)
|-
|[[#International avoirdupois ounce|International avoirdupois ounce]]
|align=right|{{cvt|1|oz|g|9|disp=number|comma=gaps}}
|align=right|{{cvt|1|oz|gr|1|disp=number|comma=gaps}}
|-
|[[#International troy ounce|International troy ounce]]
|align=right rowspan=2|{{cvt|1|ozt|g|7|disp=number|comma=gaps}}
|align=right rowspan=2|{{cvt|1|ozt|gr|0|disp=number|comma=gaps}}
|-
|[[Apothecaries' ounce]]
|-
|[[#Maria Theresa ounce|Maria Theresa ounce]]
|{{cvt|28.0668|g|gr|disp=table}}
|-
|[[#Spanish ounce|Spanish ounce]] ({{lang|es|onza}})
|align=right|28.75||&nbsp;
|-
|[[Units of measurement in France before the French Revolution#Mass|French ounce]] ({{lang|fr|once}})
|align=right|30.59||&nbsp;
|-
|[[Portuguese ounce]] ({{lang|pt|onça}})
|align=right|28.69||&nbsp;
|-
|[[Roman ounce|Roman/Italian ounce]] ({{lang|it|oncia}})
|align=right|27.4||&nbsp;
|-
|[[Dutch metric ounce]] ({{lang|nl|ons}})
|align=right|100||&nbsp;
|-
|[[Dutch (pre-metric) ounce]] ({{lang|nl|ons}})
|align=right|ca. 30||&nbsp;
|-
|[[Chinese metric ounce]] ({{lang|zh|盎司}})
|align=right|50||&nbsp;
|-
|English [[#Tower ounce|Tower ounce]]
|align=right|29.16
|align=right|450
|}

=== Active use ===
==== International avoirdupois ounce ====
The international avoirdupois ounce (abbreviated oz) is defined as exactly 28.349523125&nbsp;g under the [[international yard and pound]] agreement of 1959, signed by the United States and countries of the [[Commonwealth of Nations]].

In the [[avoirdupois]] system, sixteen ounces make up an [[Pound (mass)#Avoirdupois pound|avoirdupois pound]], and the avoirdupois pound is defined as 7000 [[grain (unit)|grains]]; one avoirdupois ounce is therefore equal to 437.5 grains.

The ounce is still a standard unit in the United States. In the United Kingdom it ceased to be an independent unit of measure in 2000,<ref>{{cite web |url=http://www.opsi.gov.uk/si/si1995/Uksi_19951804_en_1.htm |title=The Units of Measurement Regulations 1995 (Article 3) |date=20 September 2000           |access-date=4 October 2022 |quote=the provision shall, unless the context otherwise requires, be construed on or after that date as if the indication of quantity concerned were expressed in the corresponding metric unit.}}</ref> but may still be seen as a general indicator of portion sizes in burger and steak restaurants.

==== International troy ounce ====
{{Main|Troy ounce}}
A [[troy ounce]] (abbreviated oz t) is equal to 480 [[Grain (unit)|grains]].  Consequently, the '''international troy ounce''' is equal to exactly 31.1034768&nbsp;grams.  There are 12 troy ounces in the obsolete [[Pound (mass)#Troy pound|troy pound]].

The troy ounce is used only to express the mass of precious metals such as [[gold]], [[platinum]], [[palladium]], [[rhodium]] or [[silver]]. [[Bullion coin]]s are the most common products marketed in troy ounces, but precious metal bars also exist in gram and kilogram (kg) sizes. (A kilogram bullion bar contains {{convert|1|kg|ozt|sigfig=5|disp=out|abbr=off}}.)

For historical measurement of gold,
* a '''fine ounce''' is a troy ounce of pure gold content in a gold bar, computed as [[fineness]] multiplied by gross weight<ref>{{cite web|last=London Bullion Market Association|title=Market Basics|url=http://www.lbma.org.uk/pages/index.cfm?page_id=17|url-status=dead|archive-url=https://web.archive.org/web/20120308170239/http://www.lbma.org.uk/pages/index.cfm?page_id=17|archive-date=8 March 2012}}</ref>
* a '''standard ounce''' is a troy ounce of 22 [[Carat (purity)|carat]] gold, 91.66% pure (an 11 to 1 proportion of gold to [[alloy]] material)

==== Metric ounces ====
Some countries have redefined their ounces in the [[metric system]].<ref>{{cite book |first1=D. A. |last1=Wittop Koning |first2=G. M. M. |last2=Houben |title=2000 jaar gewichten in de nederlanden|language=nl |publisher=De Tijdstroom |location=Lochem-Poperinge |year=1980 |isbn=9060879651 }} {{in lang|nl}}</ref>  For example, the German apothecaries' ounce of 30 grams is very close to the previously widespread Nuremberg ounce, but the divisions and multiples come out in metric.

In 1820, the Dutch redefined their ounce (in [[Dutch language|Dutch]], ''ons'') as 100 [[gram]]s.  In 1937 the IJkwet of the Netherlands officially abolished the term, but it is still commonly used.<ref>{{cite web|url=http://www.outpostthehague.com/relocations/insideguide/wheretoturn.htm |title=Guide to The Hague – Where to turn |access-date=1 January 2008 |archive-url=https://web.archive.org/web/20080316071124/http://www.outpostthehague.com/relocations/insideguide/wheretoturn.htm |archive-date=16 March 2008 |url-status=dead }}</ref><ref>[[:nl:Nederlands metriek stelsel]]</ref> 
Dutch amendments to the metric system, such as an ''ons'' or 100&nbsp;grams, has been inherited, adopted, and taught in [[Indonesia]] beginning in elementary school. It is also listed as [[Standard language|standard usage]] in Indonesia's national dictionary, the ''[[Kamus Besar Bahasa Indonesia]]'', and the government's official elementary-school curriculum.<ref>{{Cite web |url=https://kbbi.kemdikbud.go.id/entri/ons |title=Ons in KBBI |access-date=12 July 2019 |archive-date=12 July 2019 |archive-url=https://web.archive.org/web/20190712173704/https://kbbi.kemdikbud.go.id/entri/ons |url-status=live }}</ref>

=== Historical ===

==== Apothecaries' ounce ====
The [[Apothecaries' system|apothecaries']] ounce (abbreviated ℥<!--({{U+}}2125)-->) equivalent to the troy ounce, was formerly used by [[apothecary|apothecaries]], and is thus obsolete.

==== Maria Theresa ounce ====
"Maria Theresa ounce" was once introduced in Ethiopia and some European countries, which was equal to the weight of one [[Maria Theresa thaler]], or 28.0668 g.<ref>{{Cite book
| last = Greenfield
| first = Richard
| year = 1965
| title = Ethiopia: a new political history
| publisher = F. A. Praeger
| page = 327
| url= https://books.google.com/books?id=T2MFAAAAIAAJ&q=%22Maria+theresa+ounce%22
}}</ref><ref>{{Cite book
| year = 1962
| title = Ethiopia observer
| volume = 6
| pages = 187–8
| url= https://books.google.com/books?id=EfvRAAAAMAAJ&q=%22Maria+theresa+ounce%22
}}</ref> Both the weight and the value are the definition of one ''birr'', still in use in present-day Ethiopia and formerly in Eritrea.{{Citation needed|date=December 2007}}

==== Spanish ounce ====
{{Further|Spanish customary units}}
The Spanish pound ({{langx|es|libra}}) was 460&nbsp;g.<ref>''Diccionario de la Real Academia Española'', 23rd edition, [http://buscon.rae.es/draeI/SrvltObtenerHtml?IDLEMA=45615&NEDIC=Si libra] {{Webarchive|url=https://web.archive.org/web/20110720145109/http://buscon.rae.es/draeI/SrvltObtenerHtml?IDLEMA=45615&NEDIC=Si |date=20 July 2011 }}</ref> The Spanish ounce (Spanish {{lang|es|onza}}) was {{frac|1|16}} of a pound, i.e. 28.75&nbsp;g.<ref>''Diccionario de la Real Academia Española'', 23rd edition, [http://buscon.rae.es/draeI/SrvltObtenerHtml?IDLEMA=82285&NEDIC=Si onza] {{Webarchive|url=https://web.archive.org/web/20110720145123/http://buscon.rae.es/draeI/SrvltObtenerHtml?IDLEMA=82285&NEDIC=Si |date=20 July 2011 }}</ref> It was further subdivided into 16 {{lang|es|[[adarme]]s}} (each 1.8 grams). For pharmaceutical use, the Greek {{lang|es|[[drachm|dracma]]}} was used, subdividing the Spanish ounce into 8 (3.6 grams), due to being equivalent to {{frac|1|12}} of an avoirdupois ounce. In either case, it could be further subdivided into [[Grain (unit)|grains]], each one 49.9 milligrams.

==== Tower ounce<span class="anchor" id="Tower ounce"></span> ==== <!--linked-->
The Tower ounce of {{convert|450|gr|g|abbr=off}} was a fraction of the [[tower pound]] used in the English mints, the principal one being in the Tower of London.  It dates back to the Anglo-Saxon coinage weight standard. It was abolished in favour of the Troy ounce by Henry VIII in 1527.<ref>{{cite book |first=Robert |last=Slater |title=An Inquiry into the Principles involved in the Decimalization of the Weights, Measures, and Monies of the United Kingdom |location=London |publisher=Arthur Hall |date=1855 |page=11 |url=https://books.google.com/books?id=nctVAAAAcAAJ&pg=PA11}}</ref>

==Ounce-force==
{{Main|Pound-force}}
An ounce-force is {{frac|16}} of a pound-force, or about {{convert|1/16|lbf|N|7|abbr=off|lk=out|disp=output only}}. It is defined as the force exerted by a [[mass]] of one avoirdupois ounce under [[standard gravity]] (at the surface of the earth, its [[weight]]).

The "ounce" in "ounce-force" is equivalent to an avoirdupois ounce; ounce-force is a measurement of force using avoirdupois ounces.  It is customarily not identified or differentiated.  The term has limited use in engineering calculations to simplify unit conversions between mass, force, and acceleration systems of calculations.

==Fluid ounce==
{{Main|Fluid ounce}}
A fluid ounce (abbreviated fl oz, fl. oz. or oz. fl.) is a unit of [[volume]]. An imperial fluid ounce is defined in British law as exactly 28.4130625&nbsp;[[millilitre]]s,<ref>{{cite web | title=The Units of Measurement Regulations 1995 {{!}} RELEVANT IMPERIAL UNITS, CORRESPONDING METRIC UNITS AND METRIC EQUIVALENTS |url=https://www.legislation.gov.uk/uksi/1995/1804/schedule/made |publisher=Government of the United Kingdom |date=1995 |access-date=4 October 2022}}</ref> while a [[US customary]]  fluid ounce is exactly 29.5735295625&nbsp;mL,<ref>{{cite web |title= Handbook 44 – 2018 {{!}} Appendix C. General Tables of Units of Measurement |page=C-15 |url=https://www.nist.gov/system/files/documents/2017/12/07/appc-18-hb44-final.pdf |date=2017 |access-date=4 October 2022 |publisher=[[NIST]]}}</ref> and a US food labelling fluid ounce is 30&nbsp;mL.<ref>{{cite web |title=Guidance for Industry: Guidelines for Determining Metric Equivalents of Household Measures |url=https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-guidelines-determining-metric-equivalents-household-measures |date=October 1993  |access-date=4 October 2022 |publisher=[[Food and Drugs Administration]]}}</ref> The fluid ounce is sometimes referred to simply as an "ounce" in contexts where its use is implicit, such as [[bartending]].

== Other uses ==

=== Fabric weight ===
Ounces are also used to express the "weight", or more accurately the [[areal density]], of a textile fabric in North America, Asia, or the UK, as in "''16 oz denim''". The number refers to the weight in ounces of a given amount of fabric, either a yard of a given width, or a square yard, where the depth of the fabric is a fabric-specific constant.<ref>{{cite web |url=http://www.fashiondex.com/howtos/htstfm4.php|title=How to shop the fabric market |access-date=10 December 2008 }}</ref>

{| class="wikitable"
|-
! Fabric type !! Typical weight in ounces
|-
|[[Organza]], [[voile]], [[chiffon (fabric)|chiffon]]|| align="center" | 1–3
|-
| Most [[cotton]]s, [[wool]]s, [[silk]]s, [[muslin]], [[linen]]||align="center" | 4–7
|-
|[[Denim]], [[corduroy]], [[twill]], [[velvet]]||align="center" | 7–16
|}

=== Copper layer thickness of a printed circuit board ===
The most common unit of measure for the copper thickness on a [[printed circuit board]] (PCB) is ounces (oz), as in mass. It is the resulting thickness when the mass of copper is pressed flat and spread evenly over a one-square-foot area. 1 oz will roughly equal 34.7&nbsp;μm.<ref>{{cite web |url=http://www.pcbuniverse.com/pcbu-tech-tips.php?a=4|access-date=13 November 2016 |title=Copper Thickness FAQ}}</ref>

== Notes and references ==
{{Reflist}}

== External links ==
* [https://web.archive.org/web/20180818124536/http://www.unc.edu/~rowlett/units/dictO.html#ounce Dictionary of Units: Ounce]

{{Imperial units}}
{{United States Customary Units}}
{{Authority control}}

[[Category:Customary units of measurement in the United States]]
[[Category:Imperial units]]
[[Category:Units of mass]]