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Acres to hectares converter

Convert acres to hectares (acres to hectares) with the exact factor, a conversion chart and worked steps.

Updated Checked against 3 worked examples

ac
Try
Hectares
ha
Hectares: 4.0468564224 ha
Shown to 12 significant figures, half-up
Conversion
10 ac = 4.0468564224 ha
1 ha in acres
2.471053815ac

10 acres is 4.0468564224 hectares. Going the other way, 1 ha is 2.47105381 ac.

Acres to hectares

0100200200400600acha10 → 4.0469
Acres to hectares chart (11 rows)
AcresHectares
0.10.0405
0.250.1012
0.50.2023
10.4047
20.8094
52.0234
104.0469
208.0937
4016.1874
10040.4686
640258.9988
How it's calculated S
  1. Conversion factor

    1 ac=0.40468564224 ha1\ \text{ac} = 0.40468564224\ \text{ha}

    Exact by definition.

  2. Multiply

    10×0.40468564224=4.0468564224 ha10 \times 0.40468564224 = 4.0468564224\ \text{ha}

About the acres to hectares converter

An acreage describes land area, not its shape or boundary length. The same acreage can have many different perimeters. Convert the recorded parcel area when comparing land listings, and consult the survey itself for legal boundaries or historical measurement conventions.

One acre is exactly 0.4046856422 hectares, so 10 ac is 4.046856 ha. To convert acres to hectares, multiply by 0.4046856422; to convert back, multiply by 2.4710538147.

The international acre is exactly 43,560 square feet, which is 4,046.8564224 m². Because both units are defined exactly, the factor above is exact and the results here carry no conversion error.

Worked examples

10 ac to ha

Acres (ac)
10 ac
Hectares
4.0468564224 ha

Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

1 ac to ha

Acres (ac)
1 ac
Hectares
0.40468564224 ha

Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

100 ac to ha

Acres (ac)
100 ac
Hectares
40.468564224 ha

Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

Questions

When would I convert acres to hectares?

An acreage describes land area, not its shape or boundary length. The same acreage can have many different perimeters. Convert the recorded parcel area when comparing land listings, and consult the survey itself for legal boundaries or historical measurement conventions.

How many hectares are in a acre?

One acre is exactly 0.4046856422 hectares. The international acre is exactly 43,560 square feet, which is 4,046.8564224 m².

How do you convert acres to hectares?

Multiply the number of acres by 0.4046856422. For example, 10 ac × 0.4046856422 = 4.046856 ha. To go the other way, divide by 0.4046856422.

How can I estimate acres to hectares without a calculator?

Multiply by 0.4. That is 1.2% low of the exact factor 0.4046856422, so 10 ac comes out as 4 ha instead of 4.0469.

How accurate is the acres to hectares converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “10 ac to ha” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.

About this calculator

hectares=acres×0.40468564224\text{hectares} = \text{acres} \times 0.40468564224

Sources

  1. NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B
  2. NIST Handbook 44, Appendix C: General tables of units of measurement
  3. BIPM, The International System of Units (SI Brochure), 9th edition

Checked against references

3 worked examples with independently sourced answers ship with this calculator. They run in the test suite; you can run them here too.

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