Fifth (unit)

A fifth is a unit of volume formerly used for wine and distilled beverages in the United States, equal to one fifth of a US liquid gallon, or 25+3⁄5 U.S. fluid ounces (757 milliliters); it has been superseded by the metric bottle size of 750 mL,[1] sometimes called a metric fifth, which is the standard capacity of wine bottles worldwide and is approximately 1% smaller.

[3] After its independence, the United States continued some British measures, but altered others (e.g., the U.S. liquid gallon).

[6] At this time, one-fifth of a gallon was a common legal threshold for the difference between selling by the drink and selling by the bottle or at wholesale,[6][7][8] and thus the difference between a drinking saloon or barroom and a dry-goods store.

[citation needed] The fifth was the usual size of bottle for distilled beverages in the United States until 1980.

In 1975, the Bureau of Alcohol, Tobacco and Firearms, in cooperation with the Distilled Spirits Council of the United States, proposed metric-standard bottle sizes to take effect in January 1979, with a one-year changeover period in which both sets of sizes were legal; these standards were incorporated into Title 27 of the Code of Federal Regulations.