About the km² to mi² calculation
One square kilometer is exactly 0.386102 square miles, so converting between them is a single multiplication. Enter any value above and the result updates as you type. The usual scale for reporting the area of cities and regions. Used for land and territory area in the US and UK. One square mile is exactly 640 acres.
Formula
mi² = km² × 0.386102
1 km² = 0.386102 mi²
1 mi² = 2.59 km²Worked example
To convert 1 km², multiply by 0.386102: 1 × 0.386102 = 0.386102 mi².
Frequently asked questions
How many square miles are in a square kilometer?
There are 0.386102 square miles in one square kilometer. To convert any amount, multiply the number of square kilometers by 0.386102.
How do I convert square miles back to square kilometers?
Divide instead of multiplying, or equivalently multiply by 2.59. One square mile is 2.59 square kilometers.
Is this conversion exact?
Yes. Since the international agreement of 1959, the relationship between square kilometers and square miles 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 Kilometers: the usual scale for reporting the area of cities and regions. Square Miles: used for land and territory area in the US and UK. One square mile is exactly 640 acres.
Sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units