Convert Kilometres to Miles
Enter a distance in kilometres (km) and instantly convert it to miles (mi).
Why use a kilometres to miles calculator?
Different countries use different measurement systems. Most of the world uses kilometres, while the United States and a few others commonly use miles. A fast converter helps you avoid mental math and keeps your planning accurate whether you are travelling, running, cycling, or comparing map distances.
This calculator uses the standard conversion factor: 1 kilometre = 0.621371 miles. Just enter your value, click convert, and you get an instant, precise answer.
How the conversion works
Formula
To convert kilometres to miles, multiply kilometres by 0.621371.
Miles = Kilometres × 0.621371
Example: if you drive 50 km, then 50 × 0.621371 = 31.06855 miles.
Quick reference table
| Kilometres (km) | Miles (mi) |
|---|---|
| 1 km | 0.621 mi |
| 2 km | 1.243 mi |
| 5 km | 3.107 mi |
| 10 km | 6.214 mi |
| 21.0975 km (Half Marathon) | 13.109 mi |
| 42.195 km (Marathon) | 26.219 mi |
| 100 km | 62.137 mi |
Where this conversion is most useful
- Travel planning: Convert road signs, map routes, and speed estimates.
- Fitness goals: Compare running and cycling distances across apps and devices.
- Automotive usage: Understand odometer values and vehicle range in either unit.
- Education: Verify homework and science calculations quickly.
- International communication: Share understandable distances with global teams and clients.
Rounding and accuracy tips
For everyday use, rounding to two decimal places is usually enough. For example, 10 km = 6.21 miles. For technical tasks, keep more decimal places to reduce cumulative error.
- Use 2 decimals for casual travel and fitness discussions.
- Use 4–6 decimals for analysis or scientific work.
- Avoid repeatedly converting back and forth to prevent rounding drift.
Frequently asked questions
Is "kilometers" different from "kilometres"?
No. They are the same unit. "Kilometres" is common in British English, and "kilometers" is common in American English.
How do I convert miles back to kilometres?
Divide miles by 0.621371, or multiply miles by 1.60934.
Can I enter decimal values?
Yes. The calculator supports decimals, so values like 2.5 km or 12.75 km work perfectly.
Final thoughts
A reliable kilometres to miles converter saves time and prevents mistakes. Use the calculator above whenever you need a quick distance conversion, whether you are preparing for a race, planning a road trip, or checking map data.