Hectares to Acres

Farmland in Europe, Australia and Canada is usually listed in hectares, while the US and UK still quote acres. A 50 ha farm is about 123.6 acres and a 2 ha plot is 4.94 acres. New York's Central Park covers about 341 ha, its well-known 843 acres.

Vineyards, orchards and forestry plots are measured in hectares in most of the world. Yield figures such as metric tons per hectare need converting before they can be compared with US figures in bushels per acre, and that step involves both mass and area.

The hectare is 100 ares, and 100 hectares make one square kilometer. The BIPM accepts it for use with the SI (SI Brochure), which is why land registers can use it where everything else is in meters. On the other side, the acre's definition of 43,560 sq ft is in NIST Handbook 44.

Very large areas are easier in square kilometers or square miles: see square km to square miles, or acres to hectares for the reverse.

Forestry and conservation reports mix all of these. A wildfire of 10,000 ha is 24,711 acres, or about 38.6 sq mi, and news outlets in different countries may report the same fire in different units. Converting to one unit before comparing keeps the same event from reading as two different sizes.

A quick sense check: the acre figure should always be about two and a half times the hectare figure. If it comes out smaller, the conversion ran the wrong way.