Speed Converter
Convert km/h, mph, knots, m/s, and Mach.
Enter a value, choose the units, and see the result plus every other speed unit.
Kilometer per hour → Mile per hour
Speed Converter
Translate a speed between kilometers per hour, miles per hour, meters per second, knots, feet per second, and Mach. Drivers, runners, pilots, sailors, and physics students each use a different unit – this tool shows them all side by side.
Units in the converter
- Road: kilometer per hour (km/h), mile per hour (mph).
- Science: meter per second (m/s), centimeter per second, speed of light (c).
- US engineering: foot per second, inch per second.
- Sea and air: knot, Mach (sea level, 15 °C).
Driving abroad
Speed limits change with the border. A 100 km/h highway limit in Europe is 62.14 mph, and a 60 mph US road is 96.56 km/h. A quick mental shortcut: multiply km/h by 0.6 for a slightly low mph estimate.
| km/h | mph | m/s |
|---|---|---|
| 30 | 18.64 | 8.33 |
| 50 | 31.07 | 13.89 |
| 100 | 62.14 | 27.78 |
| 120 | 74.56 | 33.33 |
Aviation and marine speeds
Ships and aircraft use knots because one nautical mile is one minute of latitude, which makes chart navigation easy. A boat cruising at 30 kn covers 55.56 km/h, and an airliner at 250 kn below 10,000 ft is moving at 463 km/h. Mach 2, twice the speed of sound at sea level, is 1,522.41 mph.
Physics and sport examples
Sprinters are timed in m/s: 10 m/s is exactly 36 km/h. In US engineering problems 88 ft/s is exactly 60 mph. Light travels at 299,792,458 m/s, which is about 1.079 billion km/h.
Converting pace
The converter handles speed (distance per time). To work out a running pace like minutes per kilometer, convert the distance with the Length Converter and the time with the Time Converter, then divide the time by the distance.
Frequently Asked Questions
How do I convert km/h to mph?
Divide km/h by 1.609344, or multiply by about 0.621371. So 100 km/h is 62.14 mph, and 60 mph is 96.56 km/h.
What is a knot?
A knot is one nautical mile per hour: 1,852 m per hour, or about 1.852 km/h and 1.1508 mph. It is the standard speed unit at sea and in aviation.
How fast is Mach 1?
The speed of sound depends on air temperature. This converter uses 340.29 m/s, the value at sea level and 15 °C, which is 1,225.04 km/h or 661.47 knots.