About the mi² to km² calculation
One square mile is exactly 2.59 square kilometers, so converting between them is a single multiplication. Enter any value above and the result updates as you type. Used for land and territory area in the US and UK. One square mile is exactly 640 acres. The usual scale for reporting the area of cities and regions.
Formula
km² = mi² × 2.59
1 mi² = 2.59 km²
1 km² = 0.386102 mi²Worked example
To convert 1 mi², multiply by 2.59: 1 × 2.59 = 2.59 km².
Frequently asked questions
How many square kilometers are in a square mile?
There are 2.59 square kilometers in one square mile. To convert any amount, multiply the number of square miles by 2.59.
How do I convert square kilometers back to square miles?
Divide instead of multiplying, or equivalently multiply by 0.386102. One square kilometer is 0.386102 square miles.
Is this conversion exact?
Yes. Since the international agreement of 1959, the relationship between square miles and square kilometers is defined exactly rather than measured, so the only rounding here is in how many decimal places we show.
Where is each of these units used?
Square Miles: used for land and territory area in the US and UK. One square mile is exactly 640 acres. Square Kilometers: the usual scale for reporting the area of cities and regions.
Sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units