Converted speed is not a legal speed limit
Use the unit and value shown on local road signs rather than substituting a rounded converted number.
Unit converter
KM/H to MPH Converter
Convert kilometres per hour to miles per hour instantly. Kilometres per hour for road speeds. See the formula, worked examples and practical reference values.
How to convert km/h to mph
Kilometres per hour to miles per hour is useful when reading speed limits, vehicle specifications and travel speeds across metric and US or UK contexts.
Formula: mph = km/h × 0.621371
Reverse formula: km/h = mph × 1.609344
Worked example
1 km/h = 0.621371 mph
- = 0.277778 m/s
- = 0.539957 kn
Avoid these errors
Common mistakes
Do not convert distance without preserving time
Kilometres per hour and miles per hour are rates; the one-hour denominator remains part of the unit.
Useful for: Metric road, vehicle and travel speeds converted to miles per hour.
Common km/h to mph conversions
| kilometres per hour | miles per hour |
|---|---|
| 1 km/h | 0.621371 mph |
| 5 km/h | 3.106856 mph |
| 10 km/h | 6.213712 mph |
| 20 km/h | 12.427424 mph |
| 30 km/h | 18.641136 mph |
| 50 km/h | 31.06856 mph |
| 60 km/h | 37.282272 mph |
| 80 km/h | 49.709695 mph |
| 100 km/h | 62.137119 mph |
| 120 km/h | 74.564543 mph |
About the units
A kilometre per hour is a metric unit represented by km/h. A mile per hour is an imperial unit represented by mph. Calculations use the same authoritative registry as the full speed converter, retaining full precision until display.
Sources and definitions
NIST — SI units and conversion guidance
Conversion constants come from the shared EzyCalculator unit registry. See how calculations are reviewed and tested.