The hectare (/ˈhɛktɛər, -tɑːr/; SI symbol: ha) is an SI accepted metric system unit of area equal to 100 ares (10,000 m2) or 1 square hectometre (hm2) and primarily used in the measurement of land. An acre is about 0.405 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 ​1100 km2. 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 units, mentioned in Section 4.1 of the SI Brochure as a unit whose use is "expected to continue indefinitely".

The name was coined in French, from the Latin ārea.

The metric system of measurement was first given a legal basis in 1795 by the French Revolutionary government. The law of 18 Germinal, Year III (7 April 1795) defined five units of measure:

In 1960, when the metric system was updated as the International System of Units (SI), the are did not receive international recognition. The International Committee for Weights and Measures (CIPM) makes no mention of the are in the current (2006) definition of the SI, but classifies the hectare as a "Non-SI unit accepted for use with the International System of Units"

This page was last edited on 17 May 2018, at 04:38.
Reference: https://en.wikipedia.org/wiki/Hectare under CC BY-SA license.

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