Square Miles to Square Kilometers
Convert square miles to square kilometers instantly. 1 mi² = 2.5899881103 km². Includes the exact factor, a conversion table of common values and the definition of both units.
How to convert square miles to square kilometers
To convert square miles to square kilometers, multiply by 2.5899881103. The relationship is fixed, so the same factor works for any quantity — there is nothing to look up and nothing that changes with temperature, location or context.
km² = mi² × 2.5899881103
Square Miles to Square Kilometers conversion table
The values people look up most often, rounded for reading. Use the calculator above for anything in between.
| Square Miles | Square Kilometers |
|---|---|
| 1 mi² | 2.589988 km² |
| 2 mi² | 5.179976 km² |
| 3 mi² | 7.769964 km² |
| 5 mi² | 12.949941 km² |
| 10 mi² | 25.899881 km² |
| 20 mi² | 51.799762 km² |
| 25 mi² | 64.749703 km² |
| 50 mi² | 129.499406 km² |
| 100 mi² | 258.998811 km² |
| 500 mi² | 1,294.99 km² |
| 1,000 mi² | 2,589.99 km² |
What is a square mile?
640 acres. Used for counties, states and weather-warning areas.
What is a square kilometer?
One million square metres. Used for city, park and lake areas.
The formula
km² = mi² × 2.5899881103
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Square Miles to Square Kilometers
- Type the number of square miles you want to convert.
- Read the result in square kilometers straight away — there is no button to press.
- Check the table below for the values that come up most often, or reverse the conversion with the linked square kilometers to square miles page.
Square Miles to Square Kilometers — frequently asked questions
How many square kilometers are in a square mile?
One square mile equals 2.5899881103 km². km² = mi² × 2.5899881103
What is the formula to convert square miles to square kilometers?
The formula is km² = mi² × 2.5899881103. It is an exact definition rather than an approximation, so the conversion never drifts no matter how large the number.
How do I convert square kilometers back to square miles?
Divide instead of multiplying: one square kilometer is 0.3861021585 mi². The reverse converter is linked in the related tools list.
Is this conversion exact?
Yes. Both units are defined against the same base unit by international agreement, so the factor is exact — any rounding you see is only in the display, which you can widen by entering more decimal places.
Is this square miles to square kilometers free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the square miles to square kilometers.
- square miles to square kilometers
- 1 square mile to square kilometers
- how many square kilometers in a square mile
- mi²2km²
- square miles in square kilometers
- square miles to square kilometers converter
- convert square miles to square kilometers
- sq mi to square kilometers
About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 15, 2026 · Calculation runs client-side · No data collected · Report an error