Kilometers per hour to miles per hour
Type a value in kilometers per hour to see it in miles per hour straight away, or type in the second box to convert back.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Type the value in the kilometers per hour box.
- Read the result in miles per hour as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
mph = km/h × 0.6213711922
Multiply the value in kilometers per hour by 0.6213711922 to get miles per hour.
Example
To convert 25 km/h to miles per hour: 25 × 0.6213711922 = 15.5343 mph.
Conversion table
| Kilometers per hour (km/h) | Miles per hour (mph) |
|---|---|
| 1 | 0.621371 |
| 2 | 1.24274 |
| 3 | 1.86411 |
| 5 | 3.10686 |
| 10 | 6.21371 |
| 20 | 12.4274 |
| 25 | 15.5343 |
| 50 | 31.0686 |
| 100 | 62.1371 |
| 250 | 155.343 |
| 500 | 310.686 |
| 1,000 | 621.371 |
About the units
- Kilometer per hour
- Covering 1000 meters in 3600 seconds, so 1 km/h is exactly 1/3.6 m/s. It is the unit on road signs and car speedometers in most countries.
- Mile per hour
- Covering one international mile (1609.344 m) in one hour, exactly 0.44704 m/s. It is used on roads in the United States and the United Kingdom.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many miles per hour are in one kilometer per hour?
1 km/h = 0.621371 mph exactly.
How do I convert kilometers per hour to miles per hour?
Use mph = km/h × 0.6213711922. For example, 25 km/h = 15.5343 mph.
How many kilometers per hour are in one mile per hour?
1 mph = 1.60934 km/h.
How do I convert km/h to m/s in my head?
Divide by 3.6, because an hour is 3600 seconds and a kilometer is 1000 meters. For example 72 km/h is 20 m/s; multiply by 3.6 to go back.
Why do Mach values differ between sources?
The speed of sound depends on air temperature. We use 340.294 m/s at sea level and 15 °C; at 11 km altitude it is about 295 m/s, so Mach 1 is slower there.