How do I convert mph to km/h?
Type a value in either box, and the answer shows it in the other unit as you type.
- Kilometers per hour (km/h)
- 1.609344
1 mph = 1.609344 km/h.
Kilometers per hour (km/h): 1.609344. 1 mph = 1.609344 km/h.
Kilometers per hour (km/h) by miles per hour (mph)
How to calculate
Converts miles per hour (mph) to kilometers per hour (km/h) and back, with the exact unit definitions.
Example with the default inputs (Miles per hour (mph) 1): 1 mph = 1.609344 km/h.
Formula: km/h = mph × 1.609344
- 1 mile per hour = 1.609344 kilometers per hour, 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.
- Miles per hour (mph) 1 gives Kilometers per hour (km/h) 1.609344.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
- Miles per hour (mph) 60 gives Kilometers per hour (km/h) 96.56064.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
- Kilometers per hour (km/h) 96.56064 gives Miles per hour (mph) 60.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
Other questions people ask
How many kilometers per hour are in a mile per hour?
1 mile per hour is 1.609344 kilometers per hour, from the exact unit definitions (NIST SP 811).
How do I convert mph to km/h?
Multiply by 1.609344: km/h = mph × 1.609344. For example, 1 mph × 1.609344 = 1.609344 km/h.
How do I convert km/h back to mph?
Multiply by 0.621371, or type the kilometers per hour into the second box and the converter works it out. 1 kilometer per hour is 0.621371 miles per hour.
What is 60 mph in km/h?
96.56064 km/h: 60 × 1.609344. 65 mph is 104.60736 km/h, and 70 mph is 112.65408 km/h.
Why multiply by 1.609344?
A mile is exactly 1.609344 km: 5,280 feet of 0.3048 m (NIST). Both speeds count per hour, so mph × 1.609344 = km/h.