The acre conversion selector on this page selects the area/surface measurement unit to convert to starting from acres (ac). To make a conversion starting from a unit of area other than acre, simply click on the "Reset" button.
The international acre (or simply "acre") is a unit of area in the Imperial and US customary systems of units equal to 4,046.8564224 square meters (1 ac = 4,046.8564224 m2), the standard derived unit of area in the International System of Units (SI).
The international acre (ac) is also equal to 40.4685642 ares (a) or 0.404685642 hectares (ha) (units of area in the metric system), or 0.00404685642 square kilometers (km2) (a unit of area in the SI), or 43,560 square feet (sq ft), or 4,840 square yards (sq yd) or 0.0015625 square miles (sq mi), which are Imperial / US customary units of area.
The acre definition varies depending on the system of units used, as follows:
- The international acre (or simply "acre"), equal to 4,046.8564224 square meters
- The US survey acre, equal to 4,046.87261 square meters
- The Irish acre, equal to 6,555.2385 square meters
- The Cheshire acre, equal to 8,561.94417 square meters
- The Roman acre, equal to 1,260 square meters
Nowadays, the most commonly used acres for measuring areas of land are the international acre and the US survey acre.