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Speed & Velocity Converter

Convert speed between m/s, km/h, mph, knots, and more. Free online speed converter. No signup, 100% private, works in your browser.

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Speed & Velocity Converter

Universal conversion engine with resilient numeric parsing.

Result

10.000000

How it works

Speed (the scalar magnitude of motion) and velocity (speed with direction) are often used interchangeably in everyday contexts. This converter handles all common speed units used across road transport, aviation, maritime navigation, and physics.

**Unit coverage** - Metric: metres per second (m/s), kilometres per hour (km/h) - Imperial: miles per hour (mph), feet per second (ft/s) - Maritime and aviation: knots (nautical miles per hour) - Physics: speed of light in vacuum (c ≈ 299,792,458 m/s), Mach number (speed of sound, varies with altitude and temperature)

**Key conversions** - 1 m/s = 3.6 km/h - 1 mph = 1.60934 km/h = 0.44704 m/s - 1 knot = 1.852 km/h = 1.15078 mph - 60 mph = 88 ft/s (easy mental arithmetic: multiply mph by 1.467 for ft/s) - Speed of sound at sea level (15°C): ≈ 340 m/s = 1225 km/h = 761 mph = Mach 1

**Mach number** Mach 1 varies with altitude because the speed of sound changes with air temperature. At 35,000 ft cruise altitude (ISA −56.5°C), Mach 1 ≈ 295 m/s ≈ 573 knots. Commercial aircraft cruise at approximately Mach 0.78–0.85. Concorde cruised at Mach 2.04.

**Knots in navigation** One knot is exactly one nautical mile per hour. The nautical mile (1852 m) equals one arcminute of latitude, making it a natural unit for navigation with charts. Aviation uses knots for airspeed because it aligns with chart distances, ATC procedures, and international standards.

Privacy: all speed conversion runs locally in the browser. No data is transmitted.

Frequently Asked Questions

What is the difference between speed and velocity?
Speed is a scalar (magnitude only): 60 mph. Velocity is a vector (magnitude plus direction): 60 mph due north. A car driving in a circle at constant 60 mph has constant speed but constantly changing velocity because the direction changes. In everyday contexts the distinction is rarely important, but in physics equations involving displacement, acceleration, and force, velocity (the vector) is required.
How fast is Mach 1, and does it vary?
Mach 1 = the speed of sound in the medium. In air at sea level at 15°C (ISA standard): Mach 1 ≈ 340.3 m/s = 1225 km/h = 661 knots = 761 mph. At 35,000 ft cruise altitude (temperature ≈ −57°C): Mach 1 ≈ 295 m/s = 573 knots. Commercial aircraft cruise at roughly Mach 0.78–0.85. The sound barrier is altitude-dependent — which is why aircraft altitude affects their Mach number at a given indicated airspeed.
Why does aviation use knots instead of km/h or mph?
A knot (nautical mile per hour) aligns with the nautical chart system: 1 nautical mile = 1 arcminute of latitude. When pilots and controllers calculate distance and time using aeronautical charts, speed in knots directly corresponds to chart distances in nautical miles. Using km/h or mph would require conversion at every navigation step. ICAO (the international aviation authority) standardised knots globally, ensuring all aircraft and ATC worldwide use the same unit.
What speed is the speed of light, in everyday terms?
The speed of light in vacuum is 299,792,458 m/s ≈ 300,000 km/s ≈ 186,000 miles/s. In one second, light travels 7.5 times around Earth's circumference. It takes light about 8 minutes 20 seconds to reach Earth from the Sun, and about 4.24 years to reach the nearest star (Proxima Centauri) — hence the unit 'light-year' for astronomical distances.