Square Miles to Square Kilometers
A square mile is 640 acres, used to describe the area of cities, counties, and large regions in the US. A square kilometer is one million square meters, used for city, country, and large land area comparisons. 1 mi² equals ≈2.58999 km², so converting between them is a matter of multiplying by that fixed factor — type any value into the converter below and both sides update instantly as you type.
Both units belong to area, measured here against area's base unit (m²) — every other area unit on this site converts through that same reference point, which is why the table below can also be read as a quick cross-check against nearby values.
Formula
km² = mi² × ≈2.58999
mi² = km² × ≈0.386102
Worked example: 5 mi² × ≈2.58999 = ≈12.9499 km².
Conversion table
| Square Mile (mi²) | Square Kilometer (km²) |
|---|---|
| 1 mi² | ≈2.58999 km² |
| 2 mi² | ≈5.17998 km² |
| 3 mi² | ≈7.76996 km² |
| 5 mi² | ≈12.9499 km² |
| 10 mi² | ≈25.8999 km² |
| 20 mi² | ≈51.7998 km² |
| 25 mi² | ≈64.7497 km² |
| 50 mi² | ≈129.499 km² |
| 100 mi² | ≈258.999 km² |
| 250 mi² | ≈647.497 km² |
| 500 mi² | ≈1,294.99 km² |
| 1,000 mi² | ≈2,589.99 km² |
Frequently asked
- How many Square Kilometers in a square mile?
- 1 mi² equals ≈2.58999 km².
- How do I convert Square Miles to Square Kilometers?
- Multiply the value in mi² by ≈2.58999 to get km². The converter above does this instantly as you type.
- Is the conversion exact?
- Yes — Square Mile and Square Kilometer are both defined by a fixed conversion factor to area's base unit (m²), so the result shown is exact to the precision displayed, not an approximation.