area · International · Modern

hectare

haexact

Etymology/person-name origin not separately researched unless stated by standards history; current definition/conversion resolved.

Definition

Non-SI unit accepted for use with the SI; 1 ha = 10⁴ m².

One hectare is equal to 10,000 square metres.

The hectare and symbol ha were adopted by the CIPM in 1879.

Used especially to express land area.

A hectare is exactly one square hectometre.

Source tier Tier A · confidence High

m²

area · International · Modern

Coherent SI derived unit for area, equal to metre squared.

area · UK / US · Modern / historical

1 acre = 43,560 ft² = exactly 4046.8564224 m² using the international foot.

ft²

area · UK / US · Modern / historical

1 ft² = exactly 0.09290304 m².

yd²

area · UK / US · Modern / historical

1 yd² = exactly 0.83612736 m².

mi²

area · UK / US · Modern / historical

1 mi² = exactly 2,589,988.110336 m².

km²

area · International · Modern

1 km² = exactly 10^6 m².

in²

area · US / UK · Modern

1 in² = exactly 0.00064516 m².

area · South Asia · Historical–modern

Government gazetteers document bighas of different areas even within districts; Rohtak government bigha was 5/8 acre.

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