Hectare

The hectare ( /ˈhɛktɛər/ or /ˈhɛktɑr/; symbol ha) is a metric unit of area defined as 10,000 square metres (100 m by 100 m), and primarily used in the measurement of land. In 1795, when the metric system was introduced, the 'are' was defined as being 100 square metres and the hectare ('hecto-' + 'are') was thus 100 'ares' or 1/100 km2. A hectare of land is about 2.47 acres.

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, although the system is the basis for the hectare. The hectare is one of the non-SI units accepted for use with the SI units.

Read more about Hectare:  History, The Units, Conversions