Unit I I base 1 ca 1 m² 1 m² 1 a 1 dam² 102 m² 1 ha 1 hm² 104 m² 100 ha 1 km² 106 m² non-SI comparisons non-SI etric I base 2.471 acre 1 ha 104 m² 107,639 sq ft 1 ha 104 m² A hectare (symbol ha, ) is a unit of area equal to 10,000 square metres, or one square hectometre, and commonly used for measuring land area. A 100 m square is one ha. Its base unit, the are, was defined by older forms of the metric sys… (More on Hectare)