Kilometers Per Hour to Miles Per Hour
An instant kilometers per hour-to-miles per hour converter, with the formula and a reference table below.
| Kilometers Per Hour | Miles Per Hour |
|---|---|
| 1 km/h | 0.621371 mph |
| 2 km/h | 1.242742 mph |
| 3 km/h | 1.864114 mph |
| 5 km/h | 3.106856 mph |
| 10 km/h | 6.213712 mph |
| 25 km/h | 15.53428 mph |
| 50 km/h | 31.06856 mph |
| 100 km/h | 62.137119 mph |
How to use
- Enter a value in the Kilometers Per Hour field.
- The Miles Per Hour figure appears immediately — no button to press.
- Typing in the Miles Per Hour field converts back to Kilometers Per Hour the same way.
- Use the reference table for the values that come up most often.
Kilometers Per Hour to Miles Per Hour formula
The factor from kilometers per hour to miles per hour is 0.621371192.
mph = km/h × 0.621371192
Why this factor: the kilometer per hour and the mile per hour are both defined against the meter per second, so dividing one definition by the other gives 0.621371192 directly. Both definitions are set out in full below.
To go the other way, divide by 0.621371192 — or use the Miles Per Hour to Kilometers Per Hour converter, which is the same calculation reversed.
Worked example
Given 60 km/h, multiplying by 0.621371192 yields 37.282272 mph.
60 km/h × 0.621371192 = 37.282272 mph
The converter above does this for any value you type, in either direction.
What is a kilometer per hour?
Kilometers per hour is the everyday speed unit for road traffic in most of the world.
Definition: Exactly 1,000 meters per 3,600 seconds, so 1 km/h is exactly 1/3.6 m/s.
Where it is used: Speed limits, vehicle speedometers, and weather wind speeds outside the US and UK.
Worth knowing: A handy shortcut: divide km/h by 3.6 for m/s, or multiply m/s by 3.6 to go the other way.
What is a mile per hour?
Miles per hour is the road speed unit of the United States and the United Kingdom.
Definition: Exactly 0.44704 meters per second, following from the exact 1,609.344 m mile.
Where it is used: US and UK speed limits and speedometers, plus baseball pitch and tennis serve speeds.
Kilometers Per Hour vs Miles Per Hour
The kilometer per hour is a metric unit while the mile per hour is an imperial unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many miles per hour are in a kilometer per hour?
One kilometer per hour equals 0.621371192 miles per hour.
What is the formula to convert kilometers per hour to miles per hour?
Multiply the number of kilometers per hour by 0.621371192. To reverse it, divide by 0.621371192 instead.
How do I convert miles per hour back to kilometers per hour?
Divide by 0.621371192, which is the same as multiplying by 1.609344.
How many miles per hour are in 10 kilometers per hour?
10 km/h works out to 6.213712 mph.
Is there anything to watch out for with kilometers per hour?
A handy shortcut: divide km/h by 3.6 for m/s, or multiply m/s by 3.6 to go the other way.
How is the kilometer per hour defined?
Exactly 1,000 meters per 3,600 seconds, so 1 km/h is exactly 1/3.6 m/s.