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Speed Converter
Convert between km/h, mph, m/s, knots, Mach, and more.
Common Speed References
Walking pace ≈ 5 km/h (3.1 mph)
Cycling average ≈ 25 km/h (15.5 mph)
Speed limit (highway) ≈ 100–130 km/h
Commercial aircraft ≈ 900 km/h (Mach 0.85)
Sound (sea level) ≈ 1,235 km/h (767 mph)
Speed of light ≈ 1.08 billion km/h
Frequently Asked Questions
How do you convert km/h to mph?▼
Multiply km/h by 0.621371. For example, 100 km/h × 0.621371 = 62.14 mph. To go the other way, multiply mph by 1.60934.
What is a knot in speed?▼
A knot (kn) is one nautical mile per hour, equal to 1.852 km/h or 1.151 mph. It is used in maritime and aviation navigation worldwide.
What is Mach 1?▼
Mach 1 is the speed of sound, which varies by altitude and temperature. At sea level and 15°C, Mach 1 ≈ 1,235 km/h (767 mph or 340 m/s). At cruising altitude, the speed of sound is lower (~1,062 km/h).
How fast is the speed of light?▼
Light travels at exactly 299,792,458 m/s in a vacuum — approximately 1.08 billion km/h or 670 million mph. It is the universal speed limit according to special relativity.
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