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Convert between miles per hour (mph), kilometers per hour (km/h), meters per second, knots, and Mach number. Essential for driving speeds, aviation, nautical navigation, and scientific calculations.
Speed is measured in different units depending on the context. Road speed uses mph (US, UK) or km/h (most countries). Aviation and marine navigation use knots. Physics uses meters per second. Supersonic flight uses Mach numbers.
1 mile per hour = 1.60934 km/h. To convert mph to km/h, multiply by 1.60934. Common driving speed conversions: 30 mph = 48.3 km/h, 60 mph = 96.6 km/h, 70 mph = 112.7 km/h, 100 mph = 160.9 km/h.
A knot (kn) = 1 nautical mile per hour = 1.852 km/h = 1.15078 mph. Knots are used universally in aviation (airspeed) and marine navigation (boat speed). Commercial aircraft cruise at about 500 knots (926 km/h, 575 mph).
Mach 1 is the speed of sound: approximately 343 m/s = 1,235 km/h = 767 mph at sea level at 20°C. At altitude where commercial aircraft fly, the speed of sound is lower (~295 m/s at 35,000 ft). Supersonic aircraft fly above Mach 1.
| Speed | mph | km/h | m/s |
|---|---|---|---|
| Walking speed | 3.1 | 5 | 1.4 |
| City speed limit (US) | 30 | 48.3 | 13.4 |
| Highway (US) | 65 | 104.6 | 29.1 |
| Speed of sound | 767 | 1,235 | 343 |
| Cruising aircraft | 575 | 926 | 257 |