A square mile is 640 acres.
Square miles to Square Kilometers Converter — mi2 to km2
Convert Square mile (mi2) to Square Kilometer (km2) using the exact conversion factor (1 square mile = 2.58998811 square kilometer). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Square miles to Square Kilometers converter
Converter
Area Converter
Convert land, construction, mapping, survey, and scientific area units.
Context values
Some unit families need one extra value for a physically accurate result.
Square metric area unit.
Result = input x 2.58998811e+6 / 1e+6.
Area uses the square meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Square miles to Square Kilometers
Comparing Square mile and Square Kilometer is common in agriculture and real estate, where US land is typically measured in acres and most of the rest of the world uses hectares. Square mile is typically associated with united States (county, metro, and regional area reporting), while Square Kilometer is typically associated with used worldwide for city, region, and country-scale area reporting..
Formula
square kilometers = square miles × 2.58998811034
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 square kilometer equals 1000000 base units, so dividing one by the other gives the direct square mile-to-square kilometer factor of 2.58998811034.
Simple example
1 mi2 × 2.58998811 = 2.58998811 km2
1 square mile = 2.58998811 square kilometers.
Real-world example
10 mi2 × 2.58998811 = 25.8998811 km2
10 square miles = 25.8998811 square kilometers.
Conversion table
| Square mile (mi2) | Square Kilometer (km2) |
|---|---|
| 1 mi2 | 2.58998811 km2 |
| 5 mi2 | 12.94994055 km2 |
| 10 mi2 | 25.8998811 km2 |
| 25 mi2 | 64.74970276 km2 |
| 50 mi2 | 129.4994055 km2 |
| 100 mi2 | 258.998811 km2 |
Reverse conversion: Square Kilometer to Square mile
2.58998811 km2 × 0.3861021585 = 0.9999999999 mi2
2.58998811 square kilometers = 0.9999999999 square miles.
square miles = square kilometers × 0.386102158542
For a page dedicated to this direction, see Square Kilometer to Square mile.
Square mile vs. Square Kilometer
| Aspect | Square mile | Square Kilometer |
|---|---|---|
| Family | US/imperial customary unit | SI derived (metric prefix) unit |
| Typical use | US city, county, and regional area statistics | National and regional land-area statistics |
| Where it's used | United States (county, metro, and regional area reporting) | Used worldwide for city, region, and country-scale area reporting. |
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 Square Kilometer
Square Kilometer (km2) measures area. A square kilometer is one million square meters — the area of a 1 km × 1 km square. It is classified as a SI derived (metric prefix) unit.
Where it's used: Used worldwide for city, region, and country-scale area reporting.
Uses of the Square Kilometer today
- National and regional land-area statistics
- City and urban planning at large scale
- Geography and cartography
History of the Square Kilometer
Like other metric-prefixed area units, the square kilometer follows automatically from the kilometer once the meter was standardized in the 1790s French metric reform.
Historical origin. Square Kilometer 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.
Square Kilometer — sources
- BIPM SI Brochure — Coherent derived units — Basis for metric-prefixed area units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many square kilometers are in 1 square mile?
1 square mile equals 2.58998811 square kilometers, using the exact defined conversion factor rather than an estimate.
How do I convert square mile to square kilometer?
Multiply the square mile value by 2.58998811. The converter above does this instantly to whatever precision you set.
How do I convert square kilometer back to square mile?
Use the reverse factor: 1 square kilometer equals 0.3861021585 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 square kilometer?
Square Kilometer (km2) measures area. A square kilometer is one million square meters — the area of a 1 km × 1 km square. It is classified as a SI derived (metric prefix) unit.
Is the square mile to square kilometer conversion exact?
Yes. A square mile is exactly 2,589,988.110336 square meters, derived from the international mile fixed in 1959. 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)