Acres to Hectares Converter (ac to ha)

Farmland, forests and parks in the US, and many land sales in the UK, are still measured in acres, but agricultural statistics, scientific papers and land records in most other countries use hectares. The acre is 43,560 square feet, which with the international foot comes to exactly 4,046.8564224 m²; the hectare is 10,000 m². One acre is therefore about 0.4047 ha, a little over two fifths of a hectare.

Much of the American Midwest and West was surveyed into square-mile sections of 640 acres, then divided into quarter sections of 160 acres and quarter-quarters of 40 acres, the sizes that fill the chart below. Converted to hectares they become untidy numbers, about 259 ha for a section and 64.7 ha for a quarter section, which is why US and international figures rarely look alike even when they describe the same land.

How to use this tool

1. Type a value in the Acre box to see it in hectares, or type in the Hectare 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

ha = ac × 0.40468564224

ac = ha ÷ 0.40468564224

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

Example

Two conversions worked with the same factors the converter uses:

160 ac × 0.40468564224 ≈ 64.7497 ha

50 ha × 2.47105381467 ≈ 123.553 ac

Acre to Hectare chart

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

Hectare to Acre chart

The reverse direction for values people often look up.

Land divisions and parks in acres

Quick mental estimate

Multiply by 4 and divide by 10: 50 acres → 200 → 20 ha. The shortcut uses 0.4, about 1.2% below the exact 0.40469, so 50 acres really comes to 20.23 ha.

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

The two units

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.

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.