How to convert km to miles?
Type a value in either box, and the answer shows it in the other unit as you type.
- Miles (mi)
- 0.621371
1 km = 0.621371 mi.
Miles (mi): 0.621371. 1 km = 0.621371 mi.
Miles (mi) by kilometers (km)
How to calculate
Converts kilometers (km) to miles (mi) and back, with the exact unit definitions.
Example with the default inputs (Kilometers (km) 1): 1 km = 0.621371 mi.
Formula: mi = km × 0.621371192237 (the same as km ÷ 1.609344)
- 1 kilometer = 0.621371192237 miles, from the exact definitions in NIST SP 811.
- Exact on the typed decimals: at most 6 decimal places (6 significant digits below 0.0001), rounded half up; an answer of 1 billion or more shows at most 15 significant digits.
Worked examples
Each example is checked against the calculator on every build.
- Kilometers (km) 1 gives Miles (mi) 0.621371.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
- Kilometers (km) 5 gives Miles (mi) 3.106856.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
- Miles (mi) 3.106856 gives Kilometers (km) 5.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
Other questions people ask
How many miles are in a kilometer?
1 kilometer is 0.621371 miles, from the exact unit definitions (NIST SP 811).
How do I convert km to miles?
Multiply by 0.621371: mi = km × 0.621371192237 (the same as km ÷ 1.609344). For example, 1 km × 0.621371 = 0.621371 mi.
How do I convert miles back to km?
Multiply by 1.609344, or type the miles into the second box and the converter works it out. 1 mile is 1.609344 kilometers.
How many miles is 5 km?
3.106856 miles: 5 ÷ 1.609344. 10 km is 6.213712 miles.
Why divide by 1.609344?
A mile is exactly 1.609344 km: 5,280 feet of 0.3048 m (NIST).