km to miles formula
To convert kilometers to miles, multiply the number of kilometers by 0.621371192237. In symbols: mi = km × 0.621371192237.
One kilometer equals 0.621371192237 miles, and one mile equals 1.609344 kilometers. Because a mile is exactly 1.609344 km, 1 km is exactly 0.621371192 miles, a fixed ratio rather than a measured one.
Worked example
Suppose you have 5 kilometers and need the answer in miles.
- Write the formula: mi = km × 0.621371192237.
- Put in the number: 5 × 0.621371192237 = 3.106855961.
- Round to suit the job. 3.107 mi is accurate enough for most everyday uses.
So 5 km is 3.106855961 mi. To check, convert back: 3.106855961 mi is 5 km.
Common kilometers to miles values
| kilometers (km) | miles (mi) |
|---|---|
| 1 | 0.6213711922 |
| 2 | 1.242742384 |
| 5 | 3.106855961 |
| 10 | 6.213711922 |
| 20 | 12.42742384 |
| 50 | 31.06855961 |
| 100 | 62.13711922 |
Reference points
Some familiar amounts in kilometers, converted to miles:
- 5 km, a parkrun or 5K: 3.10686 mi
- 10 km, a 10K race: 6.21371 mi
- 42.195 km, an official marathon: 26.2188 mi
- 100 km, a short road trip: 62.1371 mi
Where you will use it
Running apps, race entries and speed limits outside the US are in kilometers, while American and British friends think in miles. Travel planning across borders needs this direction often.
Quick mental math
Multiply by 0.6 and add a little (about 3 percent): 10 km gives 6 and the true figure is 6.21 miles. Rule of thumb: multiply by 0.6. For 5 km this gives 3 mi against the exact 3.107, an error of 3.4 percent.
Going the other way
Need the reverse? Use the miles to km converter. For comparison, 1 mi is 1.609344 km. To compare every length unit at once, open the length converter.
Everything runs in your browser. Type any number in the box above and the result updates as you type.