About the km to mi calculation
One kilometer is exactly 0.621371 miles, so converting between them is a single multiplication. Enter any value above and the result updates as you type. The standard road-distance unit in most of the world. Road distances in the US and UK. Defined as exactly 1,609.344 metres since 1959.
Formula
mi = km × 0.621371
1 km = 0.621371 mi
1 mi = 1.6093 kmWorked example
To convert 10 km, multiply by 0.621371: 10 × 0.621371 = 6.2137 mi.
Frequently asked questions
How many miles are in a kilometer?
There are 0.621371 miles in one kilometer. To convert any amount, multiply the number of kilometers by 0.621371.
How do I convert miles back to kilometers?
Divide instead of multiplying, or equivalently multiply by 1.6093. One mile is 1.6093 kilometers.
Is this conversion exact?
Yes. Since the international agreement of 1959, the relationship between kilometers and 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?
Kilometers: the standard road-distance unit in most of the world. Miles: road distances in the US and UK. Defined as exactly 1,609.344 metres since 1959.
Sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units