# Hectare

The **hectare** (/ˈhɛktɛər, -tɑːr/; SI symbol: **ha**) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm^{2}), or 10,000 m^{2}, 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.

hectare | |
---|---|

General information | |

Unit system | Non-SI unit accepted for use with SI |

Unit of | Area |

Symbol | ha |

Conversions | |

1 ha in ... | ... is equal to ... |

SI base units: | 10^{4} m^{2} |

Imperial and US customary units | 11,960 sq yd 2.4711 acres |

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 1⁄100 km

^{2}(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 m

^{2}) and

**are**(100 m

^{2}) are not officially "accepted for use", they are still used in some contexts.