Hectare

A hectare (symbol: ha) is a metric unit of area used to measure land. One hectare equals 10,000 square metres, a square area with sides of 100 metres each. The hectare is derived from the unit 'are' (a), which equals 100 square metres; the prefix 'hecto-' means one hundred, so a hectare is 100 ares.

The hectare is not part of the base units of the International System of Units (SI), but its use with SI is permitted. It is widely used for farms, orchards, urban planning, and land ownership records, because the square metre is too small for large areas of land, while the square kilometre is too large.

Conversion and calculation

One square kilometre contains 100 hectares. Conversely, one hectare equals 0.01 square kilometres. In conversion to the imperial system, one hectare is approximately 2.47 acres. Direct conversion: 1 ha = 10,000 m² = 100 a = 0.01 km².

History

The unit 'are' was created during the establishment of the metric system in France in the late eighteenth century, designed for land measurement. Because the are was too small for practical farming use, the hectare—comprising one hundred square ares—became standard. Today it is the most widely used unit of land area in the world, particularly in official records of agricultural production and forest extent.

Use

International organizations concerned with food and agriculture report their land measurements in hectares. Reports on climate change and deforestation similarly cite hectares lost or planted. Land registries in many countries use the hectare to facilitate comparison of measurements.