Why Convert Kilometers per Hour to Miles per Hour?
Converting between kilometers per hour (km/h) and miles per hour (mph) is one of the most common speed conversions. Whether for engineering, cooking, travel, or science, knowing how to quickly convert km/h to mph saves time and prevents errors.
Speed conversions between km/h and mph 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 Kilometers per Hour to Miles per Hour
To convert kilometers per hour to miles per hour, use the following formula:
mph = km/h × 0.6213711922
Example: 1 km/h = 0.6213711922 mph
For example, 5 km/h = 3.106855961 mph, 10 km/h = 6.213711922 mph, and 100 km/h = 62.13711922 mph. Our calculator above performs this conversion instantly with full precision — no rounding errors.
Common Use Cases
- Highway speed limit (China/EU): 120 km/h = 74.56454307 mph
- Urban speed limit (most countries): 50 km/h = 31.06855961 mph
- School zone speed limit: 30 km/h = 18.64113577 mph
- High-speed train (Shinkansen / CRH): 300 km/h = 186.4113577 mph
- National road speed limit (China): 80 km/h = 49.70969538 mph
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 km/h = 0.6213711922 mph. For quick mental math, remember this base conversion.
- Quick reference: 5 km/h = 3.106855961 mph · 10 km/h = 6.213711922 mph · 25 km/h = 15.53427981 mph · 50 km/h = 31.06855961 mph · 100 km/h = 62.13711922 mph
- Bookmark this page: Save this converter for instant access. It works offline once loaded — no internet needed.
Kilometers per Hour to Miles per Hour Conversion Table
| km/h | mph |
|---|---|
| 0.01 km/h | 0.006213711922 mph |
| 0.1 km/h | 0.06213711922 mph |
| 0.5 km/h | 0.3106855961 mph |
| 1 km/h | 0.6213711922 mph |
| 2 km/h | 1.242742384 mph |
| 5 km/h | 3.106855961 mph |
| 10 km/h | 6.213711922 mph |
| 20 km/h | 12.42742384 mph |
| 50 km/h | 31.06855961 mph |
| 100 km/h | 62.13711922 mph |
| 500 km/h | 310.6855961 mph |
| 1000 km/h | 621.3711922 mph |
All values in this table are mathematically exact per NIST SP 811.