Square metric area unit.
Square Kilometers to Square miles Converter — km2 to mi2
Convert Square Kilometer (km2) to Square mile (mi2) using the exact conversion factor (1 square kilometer = 0.3861021585 square mile). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Square Kilometers to Square miles 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.
A square mile is 640 acres.
Result = input x 1e+6 / 2.58998811e+6.
Area uses the square meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Square Kilometers to Square miles
Comparing Square Kilometer and Square mile 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 Kilometer is typically associated with used worldwide for city, region, and country-scale area reporting., while Square mile is typically associated with united States (county, metro, and regional area reporting).
Formula
square miles = square kilometers × 0.386102158542
This factor comes from each unit's defined relationship to the category's base unit: 1 square kilometer equals 1000000 base units, and 1 square mile equals 2589988.11034 base units, so dividing one by the other gives the direct square kilometer-to-square mile factor of 0.386102158542.
Simple example
1 km2 × 0.3861021585 = 0.3861021585 mi2
1 square kilometer = 0.3861021585 square miles.
Real-world example
10 km2 × 0.3861021585 = 3.861021585 mi2
10 square kilometers = 3.861021585 square miles.
Conversion table
| Square Kilometer (km2) | Square mile (mi2) |
|---|---|
| 1 km2 | 0.3861021585 mi2 |
| 5 km2 | 1.930510793 mi2 |
| 10 km2 | 3.861021585 mi2 |
| 25 km2 | 9.652553964 mi2 |
| 50 km2 | 19.30510793 mi2 |
| 100 km2 | 38.61021585 mi2 |
Reverse conversion: Square mile to Square Kilometer
0.3861021585 mi2 × 2.58998811 = 0.9999999999 km2
0.3861021585 square miles = 0.9999999999 square kilometers.
square kilometers = square miles × 2.58998811034
For a page dedicated to this direction, see Square mile to Square Kilometer.
Square Kilometer vs. Square mile
| Aspect | Square Kilometer | Square mile |
|---|---|---|
| Family | SI derived (metric prefix) unit | US/imperial customary unit |
| Typical use | National and regional land-area statistics | US city, county, and regional area statistics |
| Where it's used | Used worldwide for city, region, and country-scale area reporting. | United States (county, metro, and regional area reporting) |
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.
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.
Square Kilometer — sources
- BIPM SI Brochure — Coherent derived units — Basis for metric-prefixed area units.
Square mile — sources
- NIST — International yard and pound (1959) — Basis for the modern mile and its derived area unit.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many square miles are in 1 square kilometer?
1 square kilometer equals 0.3861021585 square miles, using the exact defined conversion factor rather than an estimate.
How do I convert square kilometer to square mile?
Multiply the square kilometer value by 0.3861021585. The converter above does this instantly to whatever precision you set.
How do I convert square mile back to square kilometer?
Use the reverse factor: 1 square mile equals 2.58998811 square kilometers. You can also use the swap control in the converter above to flip the direction instantly.
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.
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.
Is the square kilometer to square mile 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 kilometer still used today?
Used worldwide for city, region, and country-scale area reporting.