The hectare (/ˈhɛktɛər, -tɑːr/; SI symbol: ha) 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 acre is about 0.405 hectares and one hectare contains about 2.47 acres.

St. Enda's GAA ground, Omagh: the playing field used in the Gaelic games of Gaelic football and hurling is a little over a hectare in size.
A visualisation of one hectare
General information
Unit systemNon-SI unit accepted for use with SI
Unit ofArea
1 ha in ...... is equal to ...
   SI base units:   104 m2
   Imperial and US customary units   11,960 sq yd
2.4711 acres
Image comparing the hectare (the small blue area at lower left) to other units. The entire yellow square is one square mile.

In 1795, when the metric system was introduced, the are was defined as 100 square metres, or one square decametre, and the hectare ("hecto-" + "are") was thus 100 ares or 1100 km2 (10,000 square metres). 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. The hectare, however, remains as a non-SI unit accepted for use with the SI and whose use is "expected to continue indefinitely". Though the dekare/decare daa (1,000 m2) and are (100 m2) are not officially "accepted for use", they are still used in some contexts.

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This article uses material from the Wikipedia article Hectare, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.