League (lea)

The league is a unit of length equal to three miles, 24 furlongs, or exactly 4828.032 metres. It is obsolete in every practical sense, surviving mainly in literature and in historical documents.

The unit originated as a measure of how far a person could walk in an hour, which explains both its rough magnitude and its variability. Ancient and medieval leagues differed widely between regions. The Roman leuga was about 2.2 kilometres. French, Spanish and Portuguese leagues each had their own values, and the Spanish legua used in colonial land grants in the Americas differed again, complicating the interpretation of old property records in Texas and the American southwest.

English usage settled on three miles, a figure that was never especially precise in practice because it depended on the mile in force at the time. Since the mile itself was fixed at 5280 feet in 1593, the league inherited that definition, giving the modern value of 4828.032 metres.

Its cultural persistence far exceeds its practical use. Jules Verne's Twenty Thousand Leagues Under the Seas measures a journey rather than a depth, a distinction frequently lost in casual reference: twenty thousand leagues is roughly 96,000 kilometres, more than twice the circumference of the Earth and vastly greater than any ocean depth. Seven-league boots appear in French fairy tales as a device for covering ground in single strides. Tennyson's Charge of the Light Brigade opens with half a league onward.

The unit was formally abolished for trade in the United Kingdom long ago and has no legal standing. It appears occasionally in nautical contexts, where the marine league of three nautical miles is a separate and slightly longer unit.

Because the unit is so variable across languages and centuries, translations of older works can mislead badly. A distance given in leagues in a Spanish colonial document, a French medieval chronicle and an English statute may differ by a factor of two, and historians working with such sources generally convert to modern units and state which league they have assumed.

One league equals 3 miles, 4828.032 metres, or 4.828032 kilometres. A brisk hour's walk covers rather less than one.

League conversion table