Square Miles to Square Kilometers Converter (mi² to km²)
1 mi² = 2.589988110336 km² exactly. Convert square miles to square kilometers for states, counties, parks and lakes, with mi² and km² charts.
Square Kilometer (km²) = Square Mile (mi²) × 2.58998811034
Square Mile (mi²): A square mile is the area of a square 1 mile on each side: 640 acres, or exactly 2.589988110336 km². It is used in the US and UK for the area of cities, counties and states.
Square Kilometer (km²): A square kilometre is the area of a square 1 km on each side: 1 000 000 m², or 100 hectares. It is used for the area of cities, lakes, countries and other large regions.
| Square Mile (mi²) | Square Kilometer (km²) |
|---|---|
| 1 | 2.58998811034 |
| 5 | 12.9499405517 |
| 10 | 25.8998811034 |
| 25 | 64.7497027584 |
| 50 | 129.499405517 |
| 100 | 258.998811034 |
In the US, the area of a city, county, state, national park or lake is usually given in square miles, while atlases, international statistics and most other countries use square kilometers. A square mile is a square one statute mile (5,280 ft) on each side. With the international foot, that is exactly 2.589988110336 km², so the kilometer figure is always about 2.59 times the mile figure.
Census figures come both as total area, which includes inland and coastal water, and as land area, which leaves water out, so check which one a source gives before comparing. Rhode Island, for example, has about 1,545 square miles in total but only about 1,034 of land. Square miles are also built into US land surveys: a section is one square mile of 640 acres, and a survey township is 36 sections.
How to use this tool
- Type a value in the Square Mile box to see it in square kilometers, or type in the Square Kilometer box to convert the other way.
- Press ⇄ to swap the two units, or Load example for a typical value.
- Check the charts below for common values; for other units, open the Area converter.
Formula
Square Kilometer (km²) = Square Mile (mi²) × 2.58998811034
Square Mile (mi²) = Square Kilometer (km²) × 0.386102158542
Both factors come from exact definitions: 1 square kilometer = 0.386102158542 square miles and 1 square mile = 2.58998811034 square kilometers (shown to 12 significant digits).
Example
Two conversions worked with the same factors the converter uses:
100 mi² × 2.58998811034 ≈ 258.999 km²
500 km² × 0.386102158542 ≈ 193.051 mi²
Square Mile to Square Kilometer chart
Common values from square miles to square kilometers, rounded to four decimal places.
| Square Mile (mi²) | Square Kilometer (km²) |
|---|---|
| 0.1 | 0.259 |
| 0.25 | 0.6475 |
| 0.5 | 1.295 |
| 1 | 2.59 |
| 2 | 5.18 |
| 3 | 7.77 |
| 5 | 12.9499 |
| 10 | 25.8999 |
| 20 | 51.7998 |
| 25 | 64.7497 |
| 36 | 93.2396 |
| 50 | 129.4994 |
| 75 | 194.2491 |
| 100 | 258.9988 |
| 200 | 517.9976 |
| 250 | 647.497 |
| 500 | 1,294.99 |
| 1,000 | 2,589.99 |
| 2,500 | 6,474.97 |
| 5,000 | 12,949.94 |
| 10,000 | 25,899.88 |
| 50,000 | 129,499.41 |
| 100,000 | 258,998.81 |
| 1,000,000 | 2,589,988.11 |
Square Kilometer to Square Mile chart
The reverse direction for values people often look up.
| Square Kilometer (km²) | Square Mile (mi²) |
|---|---|
| 1 | 0.3861 |
| 2.5 | 0.9653 |
| 5 | 1.9305 |
| 10 | 3.861 |
| 25 | 9.6526 |
| 50 | 19.3051 |
| 100 | 38.6102 |
| 250 | 96.5255 |
| 500 | 193.0511 |
| 1,000 | 386.1022 |
| 2,500 | 965.2554 |
| 5,000 | 1,930.51 |
| 10,000 | 3,861.02 |
| 100,000 | 38,610.22 |
US areas in square miles
| Area | Square Mile (mi²) | Square Kilometer (km²) |
|---|---|---|
| Section in the Public Land Survey System | 1 | 2.59 |
| Survey township, 6 miles on each side | 36 | 93.2396 |
| District of Columbia, total area (Census) | 68 | 176.1192 |
| District of Columbia as first laid out, 10 miles square | 100 | 258.9988 |
| Rhode Island, total area (Census) | 1,545 | 4,001.53 |
| Delaware, total area (Census) | 2,489 | 6,446.48 |
| Texas, total area (Census) | 268,596 | 695,660.45 |
| Alaska, total area (Census) | 665,384 | 1,723,336.65 |
Quick mental estimate
Multiply by 2.6: 100 mi² → 260 km². The shortcut runs about 0.4% above the exact factor, so 100 square miles is really about 259 km².
Use the converter or the charts when the exact figure matters.
The two units
Square Mile (mi²): A square mile is the area of a square 1 mile on each side: 640 acres, or exactly 2.589988110336 km². It is used in the US and UK for the area of cities, counties and states.
Square Kilometer (km²): A square kilometre is the area of a square 1 km on each side: 1 000 000 m², or 100 hectares. It is used for the area of cities, lakes, countries and other large regions.
Frequently asked questions
How many square kilometers are in a square mile?
Exactly 2.589988110336 km², usually rounded to 2.59. A square mile also equals 640 acres, or about 259 hectares.
Why does the area of a state differ between sources?
Sources measure differently: total area includes water, land area excludes it, and coastlines, lakes and survey methods are updated over time. The Census Bureau publishes both figures, so match the definition before converting.
How big was the original District of Columbia?
It was laid out as a square 10 miles on each side, 100 square miles straddling the Potomac. The part south of the river was returned to Virginia in 1846, which is why today's district is only about 68 square miles in total.
How precise is the result?
The converter uses the exact definitions above with browser floating-point arithmetic and shows up to 12 significant digits. The charts round to four decimal places for reading.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/square-mile-to-square-kilometer-converter/
Cite or embed this tool
kakaoCalc. (2026, November 8). Square Miles to Square Kilometers Converter (mi² to km²). https://kakao.mobile/tools/square-mile-to-square-kilometer-converter/
“Square Miles to Square Kilometers Converter (mi² to km²).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/square-mile-to-square-kilometer-converter/.
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