Why Convert Miles per Hour to Kilometers per Hour?
Converting between miles per hour (mph) and kilometers per hour (km/h) is one of the most common speed conversions. Whether for engineering, cooking, travel, or science, knowing how to quickly convert mph to km/h saves time and prevents errors.
Speed conversions between mph and km/h are essential for driving, aviation, and weather monitoring. When renting a car abroad, speed limits are posted in km/h in most countries but mph in the US and UK. Aviation and maritime industries use knots internationally. Weather reports express wind speeds differently by region — understanding these conversions can be critical during severe weather events like hurricanes and typhoons.
How to Convert Miles per Hour to Kilometers per Hour
To convert miles per hour to kilometers per hour, use the following formula:
km/h = mph × 1.609344
Example: 1 mph = 1.609344 km/h
For example, 5 mph = 8.04672 km/h, 10 mph = 16.09344 km/h, and 100 mph = 160.9344 km/h. Our calculator above performs this conversion instantly with full precision — no rounding errors.
Common Use Cases
- US interstate highway speed limit: 65 mph = 104.60736 km/h
- US residential street speed limit: 25 mph = 40.2336 km/h
- NASCAR race average speed: 100 mph = 160.9344 km/h
- US urban highway speed limit: 55 mph = 88.51392 km/h
Common Mistakes to Avoid
- Knots vs km/h vs mph: These three speed units are all commonly used but in different contexts — knots for maritime/aviation, km/h in most countries, mph in US/UK.
- Wind speed scales: Weather reports may use different units by country. A "70 mph" hurricane warning is ~113 km/h or ~61 knots.
- Speed of sound varies: Mach 1 is approximately 343 m/s at sea level but changes with altitude and temperature.
Pro Tips
- Memorize the factor: 1 mph = 1.609344 km/h. For quick mental math, remember this base conversion.
- Quick reference: 5 mph = 8.04672 km/h · 10 mph = 16.09344 km/h · 25 mph = 40.2336 km/h · 50 mph = 80.4672 km/h · 100 mph = 160.9344 km/h
- Bookmark this page: Save this converter for instant access. It works offline once loaded — no internet needed.
Miles per Hour to Kilometers per Hour Conversion Table
| mph | km/h |
|---|---|
| 0.01 mph | 0.01609344 km/h |
| 0.1 mph | 0.1609344 km/h |
| 0.5 mph | 0.804672 km/h |
| 1 mph | 1.609344 km/h |
| 2 mph | 3.218688 km/h |
| 5 mph | 8.04672 km/h |
| 10 mph | 16.09344 km/h |
| 20 mph | 32.18688 km/h |
| 50 mph | 80.4672 km/h |
| 100 mph | 160.9344 km/h |
| 500 mph | 804.672 km/h |
| 1000 mph | 1609.344 km/h |
All values in this table are mathematically exact per NIST SP 811.