Editing Gallon (section)

==Relationship to other units==
Both the US gallon and imperial gallon are divided into four quarts (''quart''er gallons), which in turn are divided into two [[pint]]s, which in turn are divided into two [[cup (unit)|cups]] (not in customary use outside the US), which in turn are further divided into two [[gill (unit)|gills]]. Thus, both gallons are equal to four quarts, eight pints, sixteen cups, or thirty-two gills.

There is a difference in that the imperial gill is further divided into five fluid ounces, whereas the US gill is divided into four fluid ounces: this means that an imperial fluid ounce is {{sfrac|20}} of an imperial pint or {{sfrac|160}} of an imperial gallon, while a US fluid ounce is {{sfrac|16}} of a US pint or {{sfrac|128}} of a US gallon. 

As an imperial fluid ounce is {{#expr: 28.4130625/29.5735295625*100 round 3}}% of a US fluid ounce, this means that one imperial gallon, quart, pint, cup and gill are all equal to {{#expr: 28.4130625/29.5735295625*5/4 round 5}} of their US counterparts.

Historically, a common bottle size for [[liquor]] in the US was the "[[Fifth (unit)|fifth]]", i.e. one-fifth of a US gallon (or 0.08% more than a "reputed quart", one-sixth of an imperial gallon). While spirit sales in the US were switched to metric measures in 1976, a 750 mL bottle is still sometimes known as a "fifth".<ref>E. Frank Henriques, ''The Signet Encyclopedia of Wine'', p. 298</ref><ref>{{cite news|url=https://www.nytimes.com/1976/10/11/archives/liquor-industry-converts-to-metric-system-liquor-industry-is.html|date=11 October 1976|title=Liquor Industry Converts to Metric System|first=Rona|last=Cherry|work=[[The New York Times]]}}</ref>

===US dry gallon===
The [[dry gallon|US dry gallon]] was defined as one-eighth of a US ''[[Winchester measure|Winchester]]'' [[bushel]] of exactly {{val|2150.42|fmt=commas}} cubic inches, i.e. 268.8025 cubic inches or {{val|4.40488377086|u=L}}.<ref>{{Cite web|url=https://keisan.casio.com/exec/system/1344320515|title=US Dry Conversion Calculator|website=High accuracy calculation for life or science.|language=en|access-date=2019-10-24|archive-date=24 October 2019|archive-url=https://web.archive.org/web/20191024225749/https://keisan.casio.com/exec/system/1344320515|url-status=dead}}</ref> 

The US dry gallon is no longer used, and is no longer included in the relevant statute, which goes from the [[Quart#US dry quart|dry quart]] to the [[peck]].<ref name="15USC205">[https://www.law.cornell.edu/uscode/search/display.html?terms=unit%20measure&url=/uscode/html/uscode15/usc_sec_15_00000205----000-notes.html ''Authorized tables'']'', US Code'', Title 15, ch. 6, subchapter I, sec. 205, accessed 19 July 2008.</ref>