Foot (unit)

===International foot===
The [[international yard and pound]] agreement of July 1959 defined the length of the international yard in the United States and countries of the [[Commonwealth of Nations]] as exactly 0.9144 [[meter]]s. Consequently, since a foot is one third of a yard, the international foot is defined to be equal to exactly 0.3048 meters. This was 2&nbsp;[[Parts per million|ppm]] shorter than the previous US definition and 1.7&nbsp;ppm longer than the previous British definition.<ref>{{cite web
 |url         = http://www.npl.co.uk/reference/faqs/on-what-basis-is-one-inch-exactly-equal-to-25.4-mm-has-the-imperial-inch-been-adjusted-to-give-this-exact-fit-and-if-so-when-(faq-length)
 |publisher   = [[National Physical Laboratory (United Kingdom)|National Physical Laboratory]]
 |title       = On what basis is one inch exactly equal to 25.4 mm? Has the imperial inch been adjusted to give this exact fit and if so when?
 |access-date  = July 24, 2012
|url-status  = dead
 |archive-url  = https://web.archive.org/web/20120807195334/http://www.npl.co.uk/reference/faqs/on-what-basis-is-one-inch-exactly-equal-to-25.4-mm-has-the-imperial-inch-been-adjusted-to-give-this-exact-fit-and-if-so-when-(faq-length)
 |archive-date = August 7, 2012
|df          = mdy-all
}}</ref>

The 1959 agreement concluded a series of step-by-step events, set off in particular by the [[British Standards Institution]]'s adoption of a scientific standard inch of 25.4 [[millimetre]]s in 1930.

====Symbol====
The IEEE standard symbol for a foot is "ft".<ref name=IEEE>{{cite web |title=Recommended Unit Symbols, SI Prefixes, and Abbreviations|url=https://www.ewh.ieee.org/soc/ias/pub-dept/abbreviation.pdf|access-date=April 7, 2021}}</ref> In some cases, the foot is denoted by a [[Prime (symbol)|prime]], often approximated by an [[apostrophe]], and the inch by a double prime; for example, 2{{nbsp}}feet 4&nbsp;inches is sometimes denoted as 2′{{nbsp}}4″.<ref name=CMOS>{{cite book| title = Chicago Manual of Style | edition = 17th | date = 2017 | publisher = University of Chicago Press | at = ¶ 10.66}}</ref>