Hectares to Acres Converter (ha to ac)

The hectare is the land unit of the metric world: 10,000 m², the area of a square 100 m on each side. Farm surveys, forest inventories, vineyard registers and planning documents in most countries use it, while American readers, and many British ones, picture land in acres. With the acre fixed at exactly 4,046.8564224 m², one hectare is about 2.4711 acres, so the acre figure is always roughly two and a half times larger.

The hectare is not itself an SI unit, but the BIPM accepts it for use with the SI, and it is the standard land unit in official statistics, including those of the UN Food and Agriculture Organization. The name comes from the are, 100 m², with the prefix hecto- for a hundred, so a hectare is 100 ares and a square kilometer is 100 hectares.

How to use this tool

1. Type a value in the Hectare box to see it in acres, or type in the Acre box to convert the other way.
2. Press ⇄ to swap the two units, or Load example for a typical value.
3. Check the charts below for common values; for other units, open the Area converter.

Formula

ac = ha ÷ 0.40468564224

ha = ac × 0.40468564224

Both factors come from exact definitions: 1 acre = 0.40468564224 hectares and 1 hectare = 2.47105381467 acres (shown to 12 significant digits).

Example

Two conversions worked with the same factors the converter uses:

2.5 ha × 2.47105381467 ≈ 6.17763 ac

640 ac × 0.40468564224 ≈ 258.999 ha

Hectare to Acre chart

Common values from hectares to acres, rounded to four decimal places.

Acre to Hectare chart

The reverse direction for values people often look up.

Areas defined in hectares

Quick mental estimate

Multiply by 2.5, then take off 1%: 40 ha → 100 → 99 acres. That uses 2.475, about 0.16% above the exact 2.47105, so 40 ha really equals 98.84 acres.

Use the converter or the charts when the exact figure matters.

The two units

Hectare (ha): The hectare is 10,000 m², the area of a square 100 metres on each side. It is accepted for use with the SI and equals 100 ares or 0.01 square kilometre.

Acre (ac): The acre used here is 43,560 international square feet, exactly 4,046.8564224 m². Historical US survey acres are slightly larger, so check the foot definition when interpreting old survey records.