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Speed Converter
Convert between km/h, mph, m/s, knots, ft/s and Mach
Reference Speeds
| Object | km/h | mph |
|---|---|---|
| Walking pace | 5 | 3.1 |
| Cycling | 25 | 15.5 |
| Car (highway) | 120 | 74.6 |
| High-speed train | 320 | 199 |
| Commercial aircraft | 900 | 559 |
| Speed of sound | 1,235 | 768 |
| Low earth orbit | 28,000 | 17400 |
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Frequently Asked Questions
What is Mach 1?
Mach 1 is the speed of sound — approximately 343 m/s (1,235 km/h / 767 mph) at sea level, 20°C. This varies with altitude and temperature.
What is a knot in speed?
A knot is 1 nautical mile per hour = 1.852 km/h = 1.151 mph. Used in aviation and maritime navigation because nautical miles align with degrees of latitude.
How fast is 100 mph in km/h?
100 mph = 160.934 km/h. Quick mental math: multiply mph by 1.6 for an approximate km/h value.
How fast is the speed of light?
The speed of light in vacuum is ~299,792,458 m/s (1.08 billion km/h). Nothing with mass can reach it — only massless particles like photons travel at c.
Why are wind speeds measured in knots?
Aviation and maritime navigation use knots because nautical miles correspond to arc-minutes of latitude, making navigation calculations simpler on charts.