How to convert acres to hectares
Apply the documented acres-to-hectares relationship below, keeping the full stored constant until the displayed result is rounded.
Acres × 0.4046856422 = Hectares
For example, 10 ac equals 4.04685642 ha.
Acres to Hectares reference table
| Acres | Hectares |
|---|---|
| 1 ac | 0.40468564 ha |
| 5 ac | 2.02342821 ha |
| 10 ac | 4.04685642 ha |
| 25 ac | 10.11714106 ha |
| 50 ac | 20.23428211 ha |
| 100 ac | 40.46856422 ha |
Method and quality checks
- Calculation
- Acres × 0.4046856422 = Hectares. The calculator keeps the stored factor through the operation and rounds only the displayed result to the selected or page-supported precision.
- Unit convention
- The factor applies to square units. Converting a side length once is not the same as converting the completed area.
- Input validation
- Finite numeric inputs are accepted. Results outside the supported numeric range are rejected instead of being displayed as valid measurements.
- Reasonableness check
- 10 ac produces 4.04685642 ha. Check the direction and approximate scale before relying on a more precise displayed value.
Deeper method: Area measurements explained.
International acres compared with hectares
This converter uses the international acre, equal to exactly 4,046.8564224 square meters. A hectare is exactly 10,000 square meters, so one international acre is approximately 0.4046856422 hectare.
- Confirm the acre definition when working with historical US survey records.
- Keep legal boundary calculations separate from rounded marketing acreage.
- Use a qualified survey and the jurisdiction's required units for title or cadastral work.
Reference: NIST revised land-area conversion factors.