Kilometers and Miles Converter
Use this calculator to convert distance in either direction. Enter a value in one field and click the matching convert button.
Understanding km vs miles
Kilometers and miles are both units used to measure distance, but they belong to different measurement systems. Kilometers are part of the metric system and are used in most countries. Miles are part of the imperial system and are still commonly used in the United States and a few other places.
If you travel, run races, compare car fuel economy, or work with maps and GPS tools, you will likely need to convert between the two. That is exactly where a quick calculator like this helps.
Conversion formulas
Kilometers to miles
To convert kilometers to miles, multiply by 0.621371.
miles = kilometers × 0.621371
Example: 10 km × 0.621371 = 6.21371 miles
Miles to kilometers
To convert miles to kilometers, multiply by 1.609344.
kilometers = miles × 1.609344
Example: 5 miles × 1.609344 = 8.04672 km
Quick conversion chart
| Kilometers | Miles | Common use |
|---|---|---|
| 1 km | 0.62 mi | Short walking distance |
| 5 km | 3.11 mi | Popular race distance |
| 10 km | 6.21 mi | Training run or city drive |
| 21.1 km | 13.1 mi | Half marathon |
| 42.2 km | 26.2 mi | Marathon |
| 100 km | 62.14 mi | Road trip segment |
When these conversions matter most
- Running and cycling: Training plans often mix metric and imperial distances.
- Driving abroad: Road signs may switch from miles to kilometers.
- Fitness apps: Some apps use miles by default while others use kilometers.
- Shipping and logistics: Distance planning can require a unified unit for reporting.
Common questions
Is 5k exactly 3 miles?
Not exactly. A 5k race is 5 kilometers, which equals about 3.11 miles.
How accurate is this calculator?
It uses the standard conversion constants used in scientific and everyday settings. Results are shown with sensible rounding for readability.
Should I round values?
For casual use, rounding to two decimals is usually enough. For technical work, keep more decimal places.
Final thoughts
The km vs miles calculator above gives you fast, accurate conversions in both directions. Bookmark it if you run, travel, or frequently compare distances across countries. A few seconds of conversion can save a lot of confusion.