Convert Square Kilometers (km²) to Square Miles (mi²)
1 square kilometer equals 0.386102 square miles.
Square Kilometer to Square Mile Converter
What Is a Square Kilometer?
The square kilometer (km²) is an SI-derived unit of area equal to exactly 1,000,000 square meters — the area of a square with 1-kilometer sides. It is the standard unit for expressing large geographic areas such as countries, cities, lakes, and national parks.
Used globally in geography, cartography, and environmental science, the square kilometer is how the United Nations, NASA, and most national statistical agencies report land and water areas. One square kilometer equals exactly 100 hectares.
Key equivalences: 1 km² = 1,000,000 m² = 100 ha = 10,000 ares.
What Is a Square Mile?
The square mile (mi²) is a unit of area in the US customary and British imperial systems. It is defined as the area of a square with sides of exactly 1 statute mile (1,609.344 m), giving an exact metric equivalent of 2,589,988.110336 m².
The square mile is the standard unit for large land areas in the United States and the United Kingdom, commonly used in geography, census data, and real estate for large tracts. One square mile equals exactly 640 acres, a statutory relationship.
Key equivalences: 1 mi² = 2,589,988.11 m² = 640 ac = 27,878,400 ft².
Square Kilometers to Square Miles Formula
The conversion factor derives from the exact definition of the statute mile:
square miles = square kilometers × 0.386102 exact
This comes from squaring the linear factor: 1 km = 0.621371 mi, so 1 km² = 0.621371² = 0.386102 mi². The inverse: 1 mi² = 2.58999 km².
Worked Example
Convert the area of France (643,801 km²) to square miles:
- Multiply: 643,801 × 0.3861 = 248,573 mi²
So France covers about 248,573 square miles — slightly smaller than Texas (268,596 mi²) and about four times the size of the UK (93,628 mi²).
Quick Estimation
For mental math, multiply km² by 0.4 — this overshoots by only 3.6%. Example: 10,000 km² × 0.4 = 4,000 mi² (exact: 3,861 mi²). Alternatively, divide km² by 2.6 for a closer approximation within 0.4%.
Common Conversions at a Glance
| Square Kilometers | Square Miles |
|---|---|
| 1 km² | 0.3861 mi² |
| 10 km² | 3.861 mi² |
| 100 km² | 38.61 mi² |
| 1,000 km² | 386.1 mi² |
| 2,590 km² (≈ 1,000 mi²) | 1,000 mi² |
| 10,000 km² | 3,861 mi² |
| 1,000,000 km² | 386,102 mi² |
Which Is Bigger: Square Kilometer or Square Mile?
A square mile is about 2.59 times larger than a square kilometer. A square kilometer covers 1,000,000 m² (100 hectares) — roughly the area of 200 football fields. A square mile covers about 2,590,000 m² — roughly the area of Manhattan below Central Park.
When You Need This Conversion
- Country and state comparisons: International references use km² (France: 643,801 km²), while US geography uses mi² (Texas: 268,596 mi²). Comparing requires conversion — France is about 248,573 mi².
- Environmental reporting: Deforestation, wildfire spread, and ice sheet loss are reported in km² by international agencies (UN, NASA) but contextualized in mi² for US audiences. A 9,000 km² Amazon fire = 3,475 mi².
- Population density: Density data uses both "per km²" and "per mi²." New York City: 11,313/mi² (4,368/km²). Converting between these is routine in cross-national urban studies.
- Natural disasters: Hurricane and flood impact zones are measured in km² by meteorological agencies but reported in mi² by US media. A storm affecting 50,000 km² covers about 19,305 mi².
Frequently Asked Questions
How many square miles are in one square kilometer?
One square kilometer equals 0.386102 square miles — roughly two-fifths of a square mile. The inverse: 1 mi² = 2.58999 km². For quick mental math, multiply km² by 0.4 (within 3.6% accuracy).
Why is the area difference larger than the length difference?
Because area is two-dimensional. While 1 km = 0.6214 mi (a 38% difference), 1 km² = 0.3861 mi² (a 61% difference). The area factor is the square of the linear factor: 0.6214² ≈ 0.3861.
How do km² relate to hectares and acres?
1 km² = exactly 100 hectares = approximately 247.1 acres. And 1 mi² = 640 acres = 259.0 ha = 2.59 km². These relationships are useful for converting between geographic and agricultural scales.
Which countries use square miles?
Only the United States, Myanmar, and Liberia primarily use square miles. The UK uses both — km² officially, but mi² in everyday speech. International organizations (UN, WHO, World Bank) report exclusively in km².
How big is a square kilometer in practical terms?
A square kilometer is a square 1,000 m on each side — about 200 football fields, or a circle with a 564-meter radius. The city of London (the financial district, not Greater London) covers about 2.9 km² (1.12 mi²).
Common Square Kilometer to Square Mile Conversions
| Square Kilometer | Square Mile | Actions |
|---|---|---|
| 1 square kilometer | 0.386102 square miles | |
| 5 square kilometers | 1.93051 square miles | |
| 10 square kilometers | 3.86102 square miles |
| Square Kilometer | Square Mile | Actions |
|---|---|---|
| 50 square kilometers | 19.3051 square miles | |
| 100 square kilometers | 38.6102 square miles | |
| 1000 square kilometers | 386.102 square miles |
Square kilometers to square miles Conversion Table
Reference table with common square kilometers to square miles conversions. All values calculated with high precision.
Square Kilometers to Square Miles Table
0.001 to 5
Square Kilometers to Square Miles Table
10 to 1000000
Square Miles to Square Kilometers Table
0.0001 to 12
Square Miles to Square Kilometers Table
1 to 100000
Looking for the reverse? Convert Square Mile to Square Kilometer
Related Area Converters
Explore other area conversion tools:
