Acres to Hectares Converter — ac to ha

Formula

How this is calculated

The acre is a unit of area used chiefly in the United States, United Kingdom and some Commonwealth countries for measuring land. It was historically defined as the area a yoke of oxen could plough in a day, and later standardised as the area of a furlong (660 ft) by a chain (66 ft) — exactly 43,560 square feet. The hectare is the metric unit used internationally for land area; it equals exactly 10,000 square meters (a 100 m × 100 m square).

The conversion is exact through the international yard and foot. One international foot is exactly 0.3048 m, one square foot is therefore 0.09290304 m², and one acre of 43,560 sq ft is 43,560 × 0.09290304 = 4046.8564224 m². Dividing by 10,000 gives the factor 0.40468564224 ha per acre — this is the exact, internationally agreed value. There is also a slightly different US survey acre (1/640 of a US survey mile), but for practical land measurement purposes the difference is negligible (less than 0.01%).

One acre is about 40.5% of a hectare, so a hectare is roughly 2.47 acres. For quick mental conversion, remember that 2.5 acres ≈ 1 hectare and 5 acres ≈ 2 hectares. The calculator also shows square meters (useful for building lots), square feet (US real estate) and square miles (large land parcels).