Square Miles to Hectares
Convert square miles (mi²) to hectares (ha). Both measure surface measurement, and the conversion comes up in real estate, farming, construction work.
The Formula
``
hectares = square miles × 258.998811034
square miles = hectares × 0.00386102158542
`
One square mile is 258.9988 hectares, and one hectare is 0.003861 square miles.
Conversion Table
| Square Miles | Hectares |
|---|---|
| 1 mi² | 258.9988 ha |
| 2 mi² | 517.9976 ha |
| 5 mi² | 1,294.99 ha |
| 10 mi² | 2,589.99 ha |
| 25 mi² | 6,474.97 ha |
| 50 mi² | 12,949.94 ha |
| 100 mi² | 25,899.88 ha |
| 500 mi² | 129,499.41 ha |
| 1,000 mi² | 258,998.81 ha |
The Other Direction
| Hectares | Square Miles |
|---|---|
| 1 ha | 0.003861 mi² |
| 2 ha | 0.007722 mi² |
| 5 ha | 0.019305 mi² |
| 10 ha | 0.03861 mi² |
| 25 ha | 0.096526 mi² |
| 50 ha | 0.193051 mi² |
| 100 ha | 0.386102 mi² |
| 500 ha | 1.9305 mi² |
| 1,000 ha | 3.861 mi² |
What Each Unit Is
Square Miles (mi²) — 640 acres, or 2.589988 square kilometres. The unit of the US Public Land Survey System, which divided the west into square-mile sections.
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
A survey township is 36 square miles- San Francisco is 47 square miles
- A hectare is about 2.47 acres
- A rugby pitch is roughly 1 hectare
Precision
The factor 258.998811034 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 squareMileToHectare = (value) => value * 258.998811034;
``
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 mi² with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 mi² becomes | Error |
|---|---|---|---|
| 0 | 259 | 35,483 | 0.0005% |
| 1 | 259 | 35,483 | 0.0005% |
| 2 | 259 | 35,483 | 0.0005% |
| 3 | 258.999 | 35,482.86 | — |
| 4 | 258.9988 | 35,482.84 | — |
The right number of significant figures is set by your input, not by the converter. If you measured square miles to three significant figures, the answer in hectares is only good to three — writing more digits claims precision the measurement never had.