The hectare is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An is about 0.405 hectare and one hectare contains about 2.47 acres.

Olympic size pools measures 50 metres long, 25 metres wide, and a minimum of 2 metres deep.