A league is a unit of length (or, rarely, area). It was long common in Europe and Latin America, but it is no longer an official unit in any nation. The league originally referred to the distance a person or a horse could walk in an hour. Since the Middle Ages, many values have been specified in several countries.

On land, the league was most commonly defined as three miles (about 4.8 km), although the length of a "mile" could vary from place to place and at different times. At sea, a league was three nautical miles (about 5.6 km). English usage also included any of the other leagues mentioned below (for example, in discussing the Treaty of Tordesillas) .

The league was used in Ancient Rome, defined as 1.5 Roman miles (7,500 Roman feet, 2.2225 km, 1.4 mi.). The origin is the "leuga gallica" (also: leuca Gallica), the league of Gaul.

The Argentine league (legua) is 5.572 km (3.462 mi) or 6,666 varas: 1 vara is 0.83 m (33 in).

In certain districts of rural Australia, particularly far west New South Wales, one league is an approximate measurement of distance travelled in one hour by motor vehicle, usually 60 to 80 km (37 to 50 mi).^{[citation needed]}

League may refer to:

Unit may refer to: