Foot (unit)

The foot (abbreviated ft.) is a unit of length measure used primarily in the United States of America, so called because it was about the length of a human foot. The unit came from customary measures in England, though its use has largely been superceded in England.

The foot has been defined in U.S. law, since 1958, to be exactly 0.3048m. However, the survey foot was defined as 1200/3937 m, which is different by about one part in 500 000; the survey foot is still in use in some legal documents.

The foot is subdivided into 12 inches. 3 feet made one yard. The chain, a traditional surveyor's unit, is 66 feet. The furlong is 660 feet. The mile is 5280 feet.

Traditional measures in many other countries also had units called "foot", of similar lengths.