Convert Square Mile to Hectare
Convert square miles to hectares instantly. 1 square mile = 258.9988110336 hectare — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Hectare to Square Mile converter for the reverse conversion.
Units explained
Square Mile
A square mile is an imperial unit of area equal to exactly 2,589,988.110336 m². It is used for measuring large land areas in the United States and the United Kingdom.
Derived by squaring the statute mile (5,280 feet). The mile was standardized via the 1959 International Yard and Pound Agreement.
Square miles are used for US and UK regional geography (county areas, lake sizes, large parks), national statistics, and military range descriptions. 1 mi² = 640 acres = 2.589988 km².
Mile dates to Roman antiquity; modern exact value standardized in 1959.
Hectare
A hectare is a metric unit of area equal to 10,000 square meters, or one square hectometer. It is the most widely used metric unit for land measurement worldwide.
Defined as 100 ares, equal to one square hectometer. The name was introduced in 1795 in France as part of the metric system.
Hectares are the standard unit for agricultural land measurement worldwide except in the US (which uses acres). 1 hectare equals 2.47105 acres. In India, hectares are used in modern agricultural census and land records alongside traditional regional units.
Adopted in France in 1795; standardized internationally through the SI system.
Square Mile to Hectare conversion formula
The relationship between square miles and hectares:
To convert square miles to hectares, multiply the value in square miles by 258.9988110336. To reverse, multiply hectares by 0.0038610216.
How to use this converter
Type a value into the calculator. The result in hectares updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Hectare to Square Mile converter for the reverse direction.
Step-by-step: convert square miles to hectares
- Write down the value in square miles (mi²).
- Multiply that value by the factor 258.9988110336.
- The product is the equivalent value in hectares (ha).
- To reverse, multiply the hectare value by 0.0038610216.
Worked examples
Example 1 — Convert 1 mi² to ha:
1 × 258.9988110336 = 258.9988110336 ha
Example 2 — Convert 100 mi² to ha:
100 × 258.9988110336 = 25899.88110336 ha
Square Mile to Hectare conversion table
Standard reference values for converting square miles to hectares:
| Square Mile [mi²] | Hectare [ha] |
|---|---|
| 0.01 | 2.5899881103 |
| 0.1 | 25.8998811034 |
| 1 | 258.9988110336 |
| 2 | 517.9976220672 |
| 3 | 776.9964331008 |
| 4 | 1035.9952441344 |
| 5 | 1294.994055168 |
| 10 | 2589.988110336 |
| 20 | 5179.976220672 |
| 30 | 7769.964331008 |
| 40 | 10359.952441344 |
| 50 | 12949.94055168 |
| 100 | 25899.88110336 |
| 500 | 129499.4055168 |
| 1000 | 258998.8110336 |
Frequently asked questions
How many hectares is 1 square mile?
How do I convert square miles to hectares?
How do I convert hectares back to square miles?
How many hectares is 100 square miles?
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Imperial / US Customary (14 units)
Sources & references
Conversion factor (1 mi² = 258.9988110336 ha) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.