Why Convert Square Miles to Square Kilometers?
Converting between square miles (mi²) and square kilometers (km²) is one of the most common area conversions. Whether for engineering, cooking, travel, or science, knowing how to quickly convert mi² to km² saves time and prevents errors.
Area conversions between mi² and km² are critical in real estate, agriculture, and urban planning. When buying property internationally, apartment sizes are quoted in square meters in most countries but square feet in the US. Agricultural land in China uses mu (亩), while Western countries use hectares or acres. Understanding area conversion helps compare real estate prices across different markets accurately.
How to Convert Square Miles to Square Kilometers
To convert square miles to square kilometers, use the following formula:
km² = mi² × 2.58998811
Example: 1 mi² = 2.58998811 km²
For example, 5 mi² = 12.94994055 km², 10 mi² = 25.8998811 km², and 100 mi² = 258.998811 km². Our calculator above performs this conversion instantly with full precision — no rounding errors.
Common Use Cases
- City area of Manhattan, NYC: 33 mi² = 85.46960764 km²
- City area of Los Angeles: 469 mi² = 1214.704424 km²
- Area of Puerto Rico: 3797 mi² = 9834.184855 km²
- One section of US public land: 1 mi² = 2.58998811 km²
Common Mistakes to Avoid
- Square vs linear: When converting area, the factor is squared. If 1 m = 3.281 ft, then 1 m² = 10.764 ft² (3.281²), not 3.281 ft².
- Hectare vs acre precision: 1 hectare = 2.471 acres. Many people round to 2.5, which introduces 1.2% error — significant for land transactions.
- Regional units: Asian countries use unique area units (畝/mu in China, 坪/pyeong in Korea/Taiwan). Don't assume universal standards.
Pro Tips
- Memorize the factor: 1 mi² = 2.58998811 km². For quick mental math, remember this base conversion.
- Quick reference: 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
- Bookmark this page: Save this converter for instant access. It works offline once loaded — no internet needed.
Square Miles to Square Kilometers Conversion Table
| mi² | km² |
|---|---|
| 0.01 mi² | 0.0258998811 km² |
| 0.1 mi² | 0.258998811 km² |
| 0.5 mi² | 1.294994055 km² |
| 1 mi² | 2.58998811 km² |
| 2 mi² | 5.179976221 km² |
| 5 mi² | 12.94994055 km² |
| 10 mi² | 25.8998811 km² |
| 20 mi² | 51.79976221 km² |
| 50 mi² | 129.4994055 km² |
| 100 mi² | 258.998811 km² |
| 500 mi² | 1294.994055 km² |
| 1000 mi² | 2589.98811 km² |
All values in this table are mathematically exact per NIST SP 811.