Convert Square Miles to Square Kilometres (mi2 to km2)
1 square mile (mi²) = 2.58998811 square kilometres (km²). 1 km² = 0.3861021585 mi². Example: 15 mi² = 15 × 2.58998811 = 38.84982166 km².
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1 mi² = 2.58998811 km²
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk square mile to square kilometre converter to paste a column from Excel.
How to Convert Square Mile to Square Kilometre
- 1 mi² = 2.58998811 km²
- 1 km² = 0.3861021585 mi²
- Example: convert 15 mi² to km²: 15 mi² = 15 × 2.58998811 km² = 38.84982166 km²
Formula
km² = mi² × 2.589988110336
Derivation from SI units:
- 1 mi² = (1609.344 m)² = 2 589 988.110336 m² = 640 acres
- 1 km² = (1000 m)² = 10⁶ m² = 100 ha
- 1 mi² = 2589988.110336 m² ÷ 1000000 m² per km² = 2.589988110336 km²
Both units are defined exactly, so the factor is exact. Square Mile definition: square mile; Square Kilometre definition: square kilometre.
Worked examples
- A reading of 2 mi² converts to 5.179976221 km².
2 mi² × 2.58998811 = 5.179976221 km² - A value of 25 mi² is 64.74970276 km².
25 mi² × 2.58998811 = 64.74970276 km²
Square Mile to Square Kilometre conversion table
| Square Miles (mi²) | Square Kilometres (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 |
| 25 mi² | 64.74970276 km² |
| 50 mi² | 129.4994055 km² |
| 100 mi² | 258.998811 km² |
| 1000 mi² | 2589.98811 km² |
Where it's used
Square Miles are used for US city and county areas, while square kilometres appear in city, lake and country areas. Both measure area, so the conversion is a fixed factor.
Square Mile to other area units
| Conversion | 1 mi² equals |
|---|---|
| square mile to square kilometre | 2.58998811 km² |
| square mile to square meter | 2589988.11 m² |
| square mile to square centimeter | 25899881100 cm² |
| square mile to square foot | 27878400 ft² |
| square mile to square inch | 4014489600 in² |
| square mile to hectare | 258.998811 ha |
| square mile to acre | 640 ac |
| square mile to square millimeter | 2589988110000 mm² |
Show 1 more units
| square mile to square yard | 3097600 yd² |
|---|
Frequently asked questions
How many square kilometres are in 1 square mile?
1 mi² = 2.58998811 km².
How do I convert square miles to square kilometres?
Multiply the value in mi² by 2.58998811. For example, 15 mi² × 2.58998811 = 38.84982166 km².
Is the mi² to km² conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "square mile (mi²)".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Square Miles to Square Kilometres (mi2 to km2). Retrieved October 25, 2026, from https://scientificconverters.com/area/square-miles-to-square-kilometers/
IEEE
Scientific Converters, "Convert Square Miles to Square Kilometres (mi2 to km2)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/area/square-miles-to-square-kilometers/