What Is the Miles to Kilometers Converter?
This tool converts a distance expressed in miles (the imperial/US customary unit) into kilometers (the metric unit). It is a universal conversion based on an internationally agreed, exact factor, so it works the same everywhere in the world.
How to Use It
Type the distance in miles into the input box and the converter instantly returns the equivalent number of kilometers. You can enter whole numbers like 26 or decimals like 3.1 — the result updates to match.
The Formula Explained
The conversion uses a single fixed factor:
$$\text{kilometers} = \text{miles} \times 1.609344$$One international mile is defined as exactly 1,609.344 meters, which is 1.609344 kilometers. Because this is a definition rather than an approximation, the result is exact for any input. To convert back the other way, divide kilometers by 1.609344.
Worked Example
Suppose you ran a marathon of 26.2 miles and want the distance in kilometers:
$$26.2 \times 1.609344 = 42.164\ldots \text{ km} \approx \mathbf{42.16 \text{ km}}$$That matches the official marathon distance of 42.195 km (the official figure rounds 26.2188 miles).
FAQ
Is 1 mile exactly 1.609344 km? Yes. The international yard and mile were defined in 1959, making one mile exactly 1,609.344 meters.
How do I convert kilometers back to miles? Divide the kilometer value by 1.609344, or multiply by approximately 0.621371.
Why do some sources say 1.61 km? 1.61 is a rounded approximation. For accurate results, especially over long distances, use the full 1.609344 factor that this calculator applies.
