Speed Unit Converter
Convert speed between mph, km/h, m/s, knots, ft/s, and Mach number with instant results.
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Frequently Asked Questions
How fast is the speed of light in km/h?
The speed of light is approximately 299,792 km/s, or about 1,079,252,848 km/h (roughly 1.08 billion km/h).
What is the difference between knots and mph?
1 knot equals 1 nautical mile per hour, which is 1.15078 mph. Knots are used in aviation and maritime navigation because nautical miles align with degrees of latitude.
What is Mach 1?
Mach 1 is the speed of sound, which varies with temperature and altitude. At sea level and 15°C it is approximately 340 m/s (1,225 km/h or 761 mph).