Square Miles to Hectares
Type a value in either box to convert between square miles and hectares. The factor is 258.999.
| Square Miles | Hectares |
|---|---|
| 1 mi² | 258.998811 ha |
| 2 mi² | 517.997622 ha |
| 3 mi² | 776.996433 ha |
| 5 mi² | 1294.994055 ha |
| 10 mi² | 2589.98811 ha |
| 25 mi² | 6474.970276 ha |
| 50 mi² | 12949.940552 ha |
| 100 mi² | 25899.881103 ha |
How to use
- Enter a value in the Square Miles field.
- The Hectares figure appears immediately — no button to press.
- Typing in the Hectares field converts back to Square Miles the same way.
- Use the reference table for the values that come up most often.
Square Miles to Hectares formula
To convert square miles to hectares, multiply by 258.998811.
ha = mi² × 258.998811
Why this factor: the square mile and the hectare are both defined against the square meter, so dividing one definition by the other gives 258.998811 directly. Both definitions are set out in full below.
To go the other way, divide by 258.998811 — or use the Hectares to Square Miles converter, which is the same calculation reversed.
Worked example
Given 50 mi², multiplying by 258.998811 yields 12949.940552 ha.
50 mi² × 258.998811 = 12949.940552 ha
The converter above does this for any value you type, in either direction.
What is a square mile?
A square mile is the area of a one-mile square, used for large land areas in the US and UK.
Definition: Exactly 2,589,988.110336 square meters, and exactly 640 acres.
Where it is used: County, state and metropolitan areas, and population density in the US.
What is a hectare?
A hectare is the standard metric unit of land area — a 100-meter square.
Definition: Exactly 10,000 square meters, which is one square hectometer.
Where it is used: Agricultural and forestry land, development sites, and land-use statistics worldwide.
Worth knowing: Roughly two and a half acres, and almost exactly the area of an international rugby pitch.
Square Miles vs Hectares
The square mile is an imperial unit while the hectare is a metric unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many hectares are in a square mile?
One square mile equals 258.998811 hectares.
What is the formula to convert square miles to hectares?
Multiply the number of square miles by 258.998811. To reverse it, divide by 258.998811 instead.
How do I convert hectares back to square miles?
Divide by 258.998811, which is the same as multiplying by 0.00386102159.
How many hectares are in 10 square miles?
10 mi² works out to 2589.98811 ha.
Is there anything to watch out for with hectares?
Roughly two and a half acres, and almost exactly the area of an international rugby pitch.
How is the square mile defined?
Exactly 2,589,988.110336 square meters, and exactly 640 acres.