Speed Converter
Convert instantly between different units.
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Speed Unit Conversions
Speed is measured in different units depending on context: mph for road travel in the U.S. and UK, km/h in most of the world, m/s in scientific contexts, and knots in maritime and aviation. This converter handles all of them instantly.
Key Conversion Factors
- 1 mph = 1.60934 km/h = 0.44704 m/s
- 1 km/h = 0.62137 mph = 0.27778 m/s
- 1 knot = 1.852 km/h = 1.15078 mph
- 1 m/s = 3.6 km/h = 2.23694 mph
- Speed of sound (at sea level): ~343 m/s = 1,235 km/h = 767 mph
Real-World Speed References
- Walking pace: ~5 km/h (3.1 mph)
- Running (recreational): ~10–12 km/h (6–7.5 mph)
- Highway speed limit (US): 65–75 mph (104–121 km/h)
- Commercial airliner cruise: ~900 km/h (560 mph)
- Usain Bolt's 100m record peak: ~44.7 km/h (27.8 mph)
What is a knot and why is it used in navigation?
A knot equals one nautical mile per hour. It's used in maritime and aviation navigation because nautical miles correspond to degrees of latitude — making navigation calculations simpler. The term "knot" comes from 17th century sailors who measured ship speed by counting the knots on a rope thrown overboard over a set time interval.
How fast is Mach 1?
Mach 1 is the speed of sound: approximately 343 m/s, 1,235 km/h, or 767 mph at sea level at 20°C. This varies with altitude and temperature — at 35,000 feet (typical cruising altitude), Mach 1 is closer to 1,062 km/h (660 mph) due to colder, thinner air. Commercial jets cruise at about Mach 0.85.