Speed & Velocity Converter
Free online calculator for converting between speed and velocity units — miles per hour (mph), kilometres per hour (km/h), metres per second (m/s), knots and Mach. Instant results for travel, aviation, physics and sports.
Speed Units Reference Table
Common speed unit equivalents. 1 mph = 1.609 km/h. Speed of sound at sea level = 340.3 m/s.
| Unit | km/h | m/s | Knots |
|---|---|---|---|
| 1 mph | 1.609 | 0.4470 | 0.8690 |
| 1 km/h | 1 | 0.2778 | 0.5400 |
| 1 m/s | 3.600 | 1 | 1.944 |
| 1 knot | 1.852 | 0.5144 | 1 |
| 1 Mach | 1,224 | 340.3 | 661.5 |
Real-World Speed Reference
| Context | Speed |
|---|---|
| Walking pace | 5 km/h (3.1 mph) |
| Cycling (leisure) | 15–20 km/h (9–12 mph) |
| City speed limit (UK) | 48 km/h (30 mph) |
| Motorway limit (UK) | 113 km/h (70 mph) |
| Highway limit (US) | 105–120 km/h (65–75 mph) |
| Commercial airliner | 900 km/h (560 mph, ~Mach 0.85) |
| Speed of sound (sea level) | 1,235 km/h (767 mph, Mach 1) |
| Space Shuttle re-entry | 28,000 km/h (17,400 mph) |
Related Searches
About Speed Units
Speed is the rate of change of position — distance divided by time. The SI unit is metres per second (m/s). In everyday use, kilometres per hour (km/h) is standard in most countries, while miles per hour (mph) is used in the US, UK, and a few others for road speeds.
Knots (nautical miles per hour) are used in aviation and maritime navigation worldwide. 1 knot = 1.852 km/h = 1.151 mph. Mach number expresses speed relative to the speed of sound — Mach 1 at sea level is approximately 1,235 km/h (767 mph), varying with temperature and altitude.
Quick conversion tips: mph × 1.609 = km/h. km/h × 0.621 = mph. For mental arithmetic: multiply mph by 8, then divide by 5 to get km/h.