Quick Answer
1 kilometer per hour (km/h) = 0.621371 miles per hour (mph), and 1 mile per hour = 1.6093 kilometers per hour. Miles per Hour is the larger unit, so the same physical amount needs a bigger number when measured in kilometers per hour. Convert either way with the live tool below or the dedicated converter pages.
Key Facts
- 1 kilometer per hour (km/h) = 0.621371 mph
- 1 mile per hour (mph) = 1.6093 km/h
- Conversion is exact multiplication - no rounding in the factor
- Table below covers common values in both directions
- Dedicated converters: km/h→mph and mph→km/h pages with live tools
Frequently Asked Questions
Which is bigger, a kilometer per hour or a mile per hour?
One kilometer per hour equals 0.621371 mph, and one mile per hour equals 1.6093 km/h. The unit with the larger factor is the physically bigger one.
How do I convert kilometers per hour to miles per hour?
Multiply by the factor: value in mph = value in km/h × 0.621371. Example: 5 km/h = 3.1069 mph. Reverse: divide by 0.621371 (or multiply by 1.6093).
Why are kilometers per hour and miles per hour different?
They are two different units measuring the same physical quantity. A kilometer per hour is defined as exactly 0.621371 mph, and a mile per hour as exactly 1.6093 km/h. Because the units differ in size, the number you write down for the same amount depends on which unit you use - the conversion factor itself is exact, with no rounding.
Is there a quick way to convert without a calculator?
Memorize the 1-to factor: 1 kilometer per hour ≈ 0.621371 mph. Then multiply. For 2 km/h that's ≈ 1.2427 mph.