Acres to Hectares
Convert acres (ac) to hectares (ha). Both measure surface measurement, and the conversion comes up in real estate, farming, construction work.
The Formula
``
hectares = acres × 0.40468564224
acres = hectares × 2.47105381467
`
One acre is 0.404686 hectares, and one hectare is 2.4711 acres.
Conversion Table
| Acres | Hectares |
|---|---|
| 1 ac | 0.404686 ha |
| 2 ac | 0.809371 ha |
| 5 ac | 2.0234 ha |
| 10 ac | 4.0469 ha |
| 25 ac | 10.1171 ha |
| 50 ac | 20.2343 ha |
| 100 ac | 40.4686 ha |
| 500 ac | 202.3428 ha |
| 1,000 ac | 404.6856 ha |
The Other Direction
| Hectares | Acres |
|---|---|
| 1 ha | 2.4711 ac |
| 2 ha | 4.9421 ac |
| 5 ha | 12.3553 ac |
| 10 ha | 24.7105 ac |
| 25 ha | 61.7763 ac |
| 50 ha | 123.5527 ac |
| 100 ha | 247.1054 ac |
| 500 ha | 1,235.53 ac |
| 1,000 ha | 2,471.05 ac |
What Each Unit Is
Acres (ac) — exactly 4,046.8564224 square metres, or one furlong by one chain. The area a yoke of oxen could plough in a day — long and thin, because turning wasted time.
Hectares (ha) — exactly 10,000 square metres, or a square 100 m on each side. The metric land unit, introduced with the metric system for agriculture and forestry.
A Sense of Scale
An American football field is 1.32 acres- A soccer pitch is about 1.8 acres
- A hectare is about 2.47 acres
- A rugby pitch is roughly 1 hectare
Doing It in Your Head
Multiply by 2, then divide by 5. That is off by 1.16% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 4.0469 ha 4 ha 40.4686 ha 40 ha
Precision
The factor 0.40468564224 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
In Code
`javascript
const acreToHectare = (value) => value * 0.40468564224;
``
Where This Conversion Comes Up
- Real estate
- Farming
- Construction
- Landscaping
- Flooring
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 ac with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 ac becomes | Error |
|---|---|---|---|
| 0 | 0 | 0 | 100.0000% |
| 1 | 0.4 | 54.8 | 1.1578% |
| 2 | 0.4 | 54.8 | 1.1578% |
| 3 | 0.405 | 55.485 | 0.0777% |
| 4 | 0.4047 | 55.4439 | 0.0035% |
The right number of significant figures is set by your input, not by the converter. If you measured acres to three significant figures, the answer in hectares is only good to three — writing more digits claims precision the measurement never had.