Hectares to Acres
Convert hectares (ha) to acres (ac). Both measure surface measurement, and the conversion comes up in real estate, farming, construction work.
The Formula
``
acres = hectares × 2.47105381467
hectares = acres × 0.40468564224
`
One hectare is 2.4711 acres, and one acre is 0.404686 hectares.
Conversion Table
| 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 |
The Other Direction
| 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 |
What Each Unit Is
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.
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.
A Sense of Scale
A hectare is about 2.47 acres- A rugby pitch is roughly 1 hectare
- An American football field is 1.32 acres
- A soccer pitch is about 1.8 acres
Doing It in Your Head
Multiply by 5, then divide by 2. That is off by 1.17% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 24.7105 ac 25 ac 247.1054 ac 250 ac
Precision
The factor 2.47105381467 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 hectareToAcre = (value) => value * 2.47105381467;
``
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 ha with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 ha becomes | Error |
|---|---|---|---|
| 0 | 2 | 274 | 19.0629% |
| 1 | 2.5 | 342.5 | 1.1714% |
| 2 | 2.47 | 338.39 | 0.0426% |
| 3 | 2.471 | 338.527 | 0.0022% |
| 4 | 2.4711 | 338.541 | 0.0019% |
The right number of significant figures is set by your input, not by the converter. If you measured hectares to three significant figures, the answer in acres is only good to three — writing more digits claims precision the measurement never had.