Hectare

Comparison of Area units
Unit	nearest SI	SI base
1 m²	1 m²	1 m²
1 ha	1 hm²	10⁴ m²
1 km²	1 km²	10⁶ m²
non-SI comparisons
non-SI	metric	SI base
2.471 acre	1 ha	10⁴ m²
107,639 ft²	1 ha	10⁴ m²

A hectare (symbol ha) is a unit of area, equal to 10,000 square meters, commonly used for measuring land area. Its base unit, the are, was defined by older forms of the metric system, but is not part of the modern metric system, the International System (SI). The Comité International des Poids et Mesures classifies the hectare as a unit that, although it is not part of the International System of Units, is expected to continue in use indefinitely, having an exact definition in terms of an SI base unit.

Definition

1 hectare = 100 ares = 10,000 square metres = (100 metres)².

Thus a hectare is the area of a square plot of land where each side of the square is 100 metres, that is, a square hectometer.

The name is a contraction of the SI prefix hecto + are; a hectare is 100 ares.

Explanation

The hectare is commonly used in many countries, especially in domains concerned with land planning and management such as agriculture, forestry, and town planning where the use of square metres would be cumbersome and unnecessarily precise. In the United States, the acre is still generally used to describe area measurements in comparable situations.