what is a hectare
From Wikipedia, the free encyclopedia. The hectare (/ËhÉktÉÉr/ or /ËhÉktÉr/ ; symbol ha) is an SI accepted metric system unit of area equal to 100 ares (10,000 m 2) and primarily used in the measurement of land. An acre is about 0.4047 hectare and one hectare contains about 2.47 acres.In 1795, when the metric system was introduced, the are was defined as 100 square metres and the hectare ( hecto-  + are) was thus 100 ares or 1â100 km 2.When the metric system was further rationalised in 1960, resulting in the International System of Units (SI), the are was not included as a recognised unit.n 1795, when the metric system was introduced, the are was defined as 100 square metres and the hectare ( hecto-  + are) was thus 100 ares or 1â100 km 2. When the metric system was further rationalised in 1960, resulting in the International System of Units (SI), the are was not included as a recognised unit.