Convert foot to league

The inch has been exactly 2.54 cm since 1959; 12 inches make a foot, 3 feet a yard and 1,760 yards a mile of 1.609 km. The US and UK still use them for heights (5 ft 10 in is 178 cm), road distances and speed limits, and the inch survives everywhere in screen sizes, wheel rims and pipe threads. Five miles are almost exactly eight kilometres, a handy road-sign rule.

Gunter's chain of 1620 tied land measure to the acre: a chain is 66 ft or 100 links, 10 chains make a furlong (the length of a furrow), 8 furlongs a mile, and an acre is one chain by one furlong. Rods (16½ ft, a quarter chain) and chains still appear in US and Canadian deeds, and furlongs in horse racing. The US survey foot, 1200/3937 m, differs from the international foot by two parts per million, which adds up over a state; it was retired for new work on 1 January 2023, though survey data and legal descriptions in survey feet remain.