Square Mile to Square Kilometer Converter
One Square Mile equals 2.58998811 Square Kilometer (1 mi2 = 2.58998811 km2). Multiply a Square Mile value by 2.58998811 to get the equivalent in Square Kilometer. Use the calculator above for instant results, or follow the formula, worked examples, and reference table below.
Formula
km2 = mi2 × 2.58998811
Multiply the Square Mile value by 2.58998811 to get the equivalent value in Square Kilometer.
Example Conversions
1 Square Mile (mi2)
2.58998811 Square Kilometer (km2)
5 Square Mile (mi2)
12.94994055 Square Kilometer (km2)
10 Square Mile (mi2)
25.8998811 Square Kilometer (km2)
25 Square Mile (mi2)
64.74970276 Square Kilometer (km2)
100 Square Mile (mi2)
258.998811 Square Kilometer (km2)
Conversion Table
| Square Mile (mi2) | Square Kilometer (km2) |
|---|---|
| 0.1 | 0.258998811 |
| 0.5 | 1.294994055 |
| 1 | 2.58998811 |
| 2 | 5.179976221 |
| 5 | 12.94994055 |
| 10 | 25.8998811 |
| 25 | 64.74970276 |
| 50 | 129.4994055 |
| 100 | 258.998811 |
| 250 | 647.4970276 |
| 500 | 1294.994055 |
| 1000 | 2589.98811 |
How to Convert Manually
Use these steps to convert Square Mile values to Square Kilometer without the calculator.
- Write down the value in Square Mile (mi2) that you want to convert.
- Multiply that value by 2.58998811.
- For example, 10 Square Mile × 2.58998811 = 25.8998811 Square Kilometer.
- Label the result as Square Kilometer (km2).
Relative Size Comparison
This chart shows the visual difference in size between exactly one Square Mile and one Square Kilometer.
About Square Mile and Square Kilometer
The square mile is 640 acres, about 2.59 square kilometers. US geography uses it for counties, cities, and large land areas. The square kilometer is one million square meters. Geography uses it for cities, lakes, parks, and countries — anything too large for hectares. One Square Mile equals 2.58998811 Square Kilometer (1 mi2 = 2.58998811 km2). Square Mile to Square Kilometer conversion comes up most often in US city and county areas and in US population density figures, typically when figures need restating for city and country land areas.
Precision and Rounding: Area factors are the squares of exact length factors, so they are exact too (1 ft² = 0.09290304 m² precisely). Whole numbers usually suffice for rooms and land parcels; surveying and legal land descriptions carry four or more decimal places.
Conversion factors per NIST Special Publication 811 and the BIPM SI Brochure (9th edition) (reference).
Worked Example
15 Square Mile equals 38.84982166 Square Kilometer.
15 mi2 × 2.58998811 = 38.84982166 km2
FAQ
How do I convert Square Mile to Square Kilometer?
Multiply the Square Mile value by 2.58998811 to get the equivalent value in Square Kilometer.
What is the formula for Square Mile to Square Kilometer?
The formula is km2 = mi2 × 2.58998811.
How many Square Kilometer are in 1 Square Mile?
1 Square Mile equals 2.58998811 Square Kilometer.
Can I convert Square Kilometer back to Square Mile?
Yes. 1 Square Kilometer equals 0.3861021585 Square Mile, and the related converter can reverse the calculation.
What are common names for Square Mile and Square Kilometer?
Square Mile is shown as mi2 and may also be searched as square miles, sq mi, mi². Square Kilometer is shown as km2 and may also be searched as square kilometers, sq km, km².
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