Acres to hectares
One ac equals 0.4046856422 ha. Type any number and the answer appears as you type — the maths happens in your browser.
Result
The same value in every unit
| Unit | Value |
|---|
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Common values
| acres | hectares |
|---|---|
| 1 ac | 0.40468564 ha |
| 2 ac | 0.80937128 ha |
| 3 ac | 1.2140569 ha |
| 5 ac | 2.0234282 ha |
| 10 ac | 4.0468564 ha |
| 15 ac | 6.0702846 ha |
| 20 ac | 8.0937128 ha |
| 25 ac | 10.117141 ha |
| 50 ac | 20.234282 ha |
| 100 ac | 40.468564 ha |
| 500 ac | 202.34282 ha |
| 1000 ac | 404.68564 ha |
How to use
- Enter the number of acres in the field.
- The result in hectares updates on every keystroke.
- Use the table below for the values people look up most often.
Formula and reverse conversion
The formula
To convert by hand: ha = ac ÷ 2.471053815. Going back the other way, one ha is 2.471053815 ac.
Where the odd number comes from
The factor is not a round number because the imperial units are defined through the metric ones by international agreement: an inch is exactly 25.4 mm and a pound is exactly 0.45359237 kg. Everything else follows from those definitions.
ha = ac ÷ 2.471053815
Frequently asked questions
How many hectares are in one acres?
One ac is 0.4046856422 ha.
How do I convert acres to hectares?
Multiply by the factor: ha = ac ÷ 2.471053815.
Is the result exact?
The factors are the exact legal definitions, and up to ten significant digits are kept in the answer. Rounding happens only in the display.
How do I convert hectares back to acres?
One ha is 2.471053815 ac — or open the reverse page linked below.