A square mile is 640 acres.
Square miles to Hectares Converter — mi2 to ha
Convert Square mile (mi2) to Hectare (ha) using the exact conversion factor (1 square mile = 258.998811 hectare). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Square miles to Hectares converter
Converter
Agriculture Converter
Convert acres, hectares, yield, seed, fertilizer, irrigation, and application-rate units.
Context values
Some unit families need one extra value for a physically accurate result.
A hectare is 10,000 square meters.
Result = input x 2.58998811e+6 / 10000.
Area units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Square miles to Hectares
Square mile and Hectare both measure a farming-related quantity — a land area or an application/yield rate per unit area — used to report crop yields, calculate how much fertilizer or seed a field needs, and plan irrigation. Square mile is typically associated with united States (county, metro, and regional area reporting), while Hectare is typically associated with used worldwide, especially in agriculture, forestry, and land statistics outside the US.
Formula
hectares = square miles × 258.998811034
This factor comes from each unit's defined relationship to the category's base unit: 1 square mile equals 2589988.11034 base units, and 1 hectare equals 10000 base units, so dividing one by the other gives the direct square mile-to-hectare factor of 258.998811034.
Simple example
1 mi2 × 258.998811 = 258.998811 ha
1 square mile = 258.998811 hectares.
Real-world example
100 mi2 × 258.998811 = 25,899.8811 ha
100 square miles = 25,899.8811 hectares.
Conversion table
| Square mile (mi2) | Hectare (ha) |
|---|---|
| 1 mi2 | 258.998811 ha |
| 5 mi2 | 1,294.994055 ha |
| 10 mi2 | 2,589.98811 ha |
| 50 mi2 | 12,949.94055 ha |
| 100 mi2 | 25,899.8811 ha |
| 500 mi2 | 129,499.4055 ha |
Reverse conversion: Hectare to Square mile
258.998811 ha × 0.003861021585 = 0.9999999999 mi2
258.998811 hectares = 0.9999999999 square miles.
square miles = hectares × 0.00386102158542
For a page dedicated to this direction, see Hectare to Square mile.
Square mile vs. Hectare
| Aspect | Square mile | Hectare |
|---|---|---|
| Family | US/imperial customary unit | non-SI metric unit accepted for use with SI |
| Typical use | US city, county, and regional area statistics | Reporting farmland and crop area in international agricultural statistics |
| Where it's used | United States (county, metro, and regional area reporting) | Used worldwide, especially in agriculture, forestry, and land statistics outside the US |
Understanding the Square mile
Square mile (mi2) measures area. A square mile is exactly 2,589,988.110336 square meters, derived from the international mile fixed in 1959. It is classified as a US/imperial customary unit.
Where it's used: United States (county, metro, and regional area reporting)
Uses of the Square mile today
- US city, county, and regional area statistics
- Population density reporting (people per square mile)
- Land-use and geography in US contexts
History of the Square mile
The square mile follows directly from the statute mile, itself fixed at exactly 1,609.344 meters by the 1959 International Yard and Pound Agreement; squaring that value gives the modern square mile.
Historical origin. Square mile was not the invention of a single named person; it developed through the process described above.
Understanding the Hectare
Hectare (ha) measures area. A hectare is exactly 10,000 square meters — the area of a 100 m × 100 m square. It is classified as a non-SI metric unit accepted for use with SI.
Where it's used: Used worldwide, especially in agriculture, forestry, and land statistics outside the US
Uses of the Hectare today
- Reporting farmland and crop area in international agricultural statistics
- Forestry and land-use planning
- Real estate and cadastral survey in metric countries
History of the Hectare
The hectare derives from the 'are,' a metric area unit (100 m²) introduced during the French Revolutionary metric reforms of the 1790s. 'Hecto-' is simply the SI prefix for 100, so a hectare is 100 ares.
Although not itself an SI unit, the hectare is officially accepted for use alongside SI units by the BIPM because of its practical importance in land measurement, and it remains the standard land-area unit in most of the world.
Historical origin. Hectare was not the invention of a single named person; it developed through the process described above.
Square mile — sources
- NIST — International yard and pound (1959) — Basis for the modern mile and its derived area unit.
Hectare — sources
- BIPM SI Brochure, 9th edition — Non-SI units accepted for use with SI — Lists the hectare as an accepted non-SI unit.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many hectares are in 1 square mile?
1 square mile equals 258.998811 hectares, using the exact defined conversion factor rather than an estimate.
How do I convert square mile to hectare?
Multiply the square mile value by 258.998811. The converter above does this instantly to whatever precision you set.
How do I convert hectare back to square mile?
Use the reverse factor: 1 hectare equals 0.0038610216 square miles. You can also use the swap control in the converter above to flip the direction instantly.
What is a square mile?
Square mile (mi2) measures area. A square mile is exactly 2,589,988.110336 square meters, derived from the international mile fixed in 1959. It is classified as a US/imperial customary unit.
What is a hectare?
Hectare (ha) measures area. A hectare is exactly 10,000 square meters — the area of a 100 m × 100 m square. It is classified as a non-SI metric unit accepted for use with SI.
Is the square mile to hectare conversion exact?
Yes. A hectare is exactly 10,000 square meters — the area of a 100 m × 100 m square. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the square mile still used today?
United States (county, metro, and regional area reporting)
What's the difference between a yield rate and an application rate?
A yield rate describes how much of a crop is harvested per unit of land area (for example, tonnes per hectare). An application rate describes how much of an input like fertilizer or seed is applied per unit of land area. Both are commonly expressed using the same kind of mass-per-area units.