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Acres to Hectares

Acres (ac) to hectares (ha).

Result4.04686ha

Precision (significant figures)

Formula

ha = ac × 0.404686

1 ac = 0.404686 ha

ha = acres × 0.40468564224 exactly. An acre is 43,560 square feet (4,046.86 m²) and a hectare is 10,000 m², so 10 acres is 4.04686 ha and a 640-acre square mile is 258.999 ha.

Formula

ha = ac × 0.404686

Worked example

  1. Start with 10 ac.
  2. Multiply by 0.404686 (ha per ac): 10 × 0.404686 = 4.04686 ha.

Acres to hectares chart

Acres (ac)Hectares (ha)
0.10.0404686
0.250.101171
0.50.202343
10.404686
20.809371
2.51.01171
52.02343
104.04686
208.09371
2510.1171
4016.1874
5020.2343
10040.4686
16064.7497
640258.999
1,000404.686

When you need this conversion

Farmland, property listings, forestry, conservation areas and planning applications. The US and UK use acres for land; most other countries use hectares.

Quick reference

  • 1 ac = 0.404686 ha
  • 5 ac = 2.02343 ha
  • 10 ac = 4.04686 ha
  • 40 ac = 16.1874 ha (a quarter-quarter section)
  • 100 ac = 40.4686 ha
  • 640 ac = 258.999 ha (1 square mile)

Rule of thumb

Divide acres by 2.5 for a close estimate: 100 acres is about 40 ha. The exact figure is 40.47.

Common mistakes

Assuming an acre is square. It’s a unit of area. Historically it was 1 furlong by 1 chain (660 × 66 ft), a long thin strip.

Mixing up the direction. A hectare is bigger: 1 ha is 2.47 acres.

For the reverse, use hectares to acres. For small lots, see square feet to acres.

Questions

How many hectares is 1 acre?

0.404686 ha, a little over 40% of a hectare.

How many hectares is 100 acres?

40.4686 ha.

How big is an acre?

4,046.86 m², about 63.6 m (208.7 ft) on each side if square, or a little over half a soccer pitch.

How many acres in a square mile?

Exactly 640.

Sources

Last reviewed 2026-09-24. How we check values · Report a problem with this page