This article is about a foot as a unit of length. For other uses of foot, see foot (disambiguation).
A foot (plural: feet) is a non-SI unit of distance or length. The popular belief is that original standard was the length of a man's foot. The average foot length is about 240 mm (9.4 in) for current Europeans. About 996 of 1000 British men have a foot that is less than 12 inches long. A plausible explanation for the missing inches is that the measure did not refer to a naked foot, but to the length of footwear. This is consistent with the measure being convenient for practical purposes such as on building sites etc. People almost always pace out lengths whilst wearing shoes or boots, rather than removing them and pacing barefoot.
There are twelve inches in one foot and three feet in one yard.
The standardization of weights and measures has left several different standardized foot measures. The most commonly used foot today is the imperial foot, which is defined to be exactly 0.3048 metres. This unit is sometimes denoted with a prime (e.g. 30′ means 30 feet), often approximated by an apostrophe. Similarly, inches can be denoted by a double prime (often approximated by a quotation mark), so 6′2″ means 6 feet 2 inches.
The foot as a measure was used in almost all cultures. The first known standard foot measure was from Sumeria, where a definition is given in a statue of Gudea of Lagash from around 2575 BC. The imperial foot was adapted from an Egyptian measure by the Greeks, with a subsequent larger foot being adopted by the Romans.
In addition to the current standard imperial foot, there is also a slightly different U.S. survey foot, used only in connection with surveys by the U.S. Coast and Geodetic Survey, defined as exactly 1200/3937 m.[1] (http://www.ngs.noaa.gov/PUBS_LIB/FedRegister/FRdoc59-5442.pdf)
This unit is used to express turbidity measured by a nephelometer that measures directly the fraction of light transmitted through a water sample as compared to the fraction transmitted through a standard preparation of formazin.
The unit is used in archery, where it measures the brace height of a bow (the distance from the center of the grip to the bowstring) and also in kayaking, where it measures various critical dimensions of the boat.
The footlambert describes the luminance of a surface that emits or reflects one lumen per square foot; it is the luminance of a perfectly reflecting surface under an illumination of one footcandle.
Template:Unit of length A foot (plural: feet) is a non-SI unit of distance or length, measuring around a third of a meter.
The most commonly used foot today is the English foot, used in the United Kingdom and the United States and elsewhere, which is defined to be exactly 0.3048 meters.
The imperialfoot was adapted from an Egyptian measure by the Greeks, with a subsequent larger foot being adopted by the Romans.
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