Square Kilometers to Square Miles
Convert square kilometers to square miles instantly — one square kilometer is 0.386102 square miles.
| Square Kilometers | Square Miles |
|---|---|
| 1 km² | 0.386102 mi² |
| 2 km² | 0.772204 mi² |
| 3 km² | 1.158306 mi² |
| 5 km² | 1.930511 mi² |
| 10 km² | 3.861022 mi² |
| 25 km² | 9.652554 mi² |
| 50 km² | 19.305108 mi² |
| 100 km² | 38.610216 mi² |
How to use
- Enter a value in the Square Kilometers field.
- The Square Miles figure appears immediately — no button to press.
- Typing in the Square Miles field converts back to Square Kilometers the same way.
- Use the reference table for the values that come up most often.
Square Kilometers to Square Miles formula
Converting square kilometers to square miles is a single multiplication by 0.386102159.
mi² = km² × 0.386102159
Why this factor: the square kilometer and the square mile are both defined against the square meter, so dividing one definition by the other gives 0.386102159 directly. Both definitions are set out in full below.
To go the other way, divide by 0.386102159 — or use the Square Miles to Square Kilometers converter, which is the same calculation reversed.
Worked example
Start with 1000 km². Multiply by 0.386102159 to get 386.102159 mi².
1000 km² × 0.386102159 = 386.102159 mi²
The converter above does this for any value you type, in either direction.
What is a square kilometer?
A square kilometer is the area of a one-kilometer square — one million square meters.
Definition: Exactly 1×10⁶ square meters. Note it is the kilometer that is squared, not the prefix applied to a square meter.
Where it is used: City, national park and country areas, population density, and land cover statistics.
What is a square mile?
A square mile is the area of a one-mile square, used for large land areas in the US and UK.
Definition: Exactly 2,589,988.110336 square meters, and exactly 640 acres.
Where it is used: County, state and metropolitan areas, and population density in the US.
Square Kilometers vs Square Miles
The square kilometer is a metric unit while the square mile is an imperial unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many square miles are in a square kilometer?
One square kilometer equals 0.386102159 square miles.
What is the formula to convert square kilometers to square miles?
Multiply the number of square kilometers by 0.386102159. To reverse it, divide by 0.386102159 instead.
How do I convert square miles back to square kilometers?
Divide by 0.386102159, which is the same as multiplying by 2.58998811.
How many square miles are in 10 square kilometers?
10 km² works out to 3.861022 mi².
How is the square kilometer defined?
Exactly 1×10⁶ square meters. Note it is the kilometer that is squared, not the prefix applied to a square meter.