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Speed converter — km/h, m/s, mph, knots, Mach

This speed converter instantly converts any value to all common speed units: kilometres per hour (km/h), metres per second (m/s), miles per hour (mph), knots (kn) used in aviation and navigation, and Mach number. Enter a value, choose the input unit, and all conversions appear at once.

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How we calculate speed

All values are converted via the common base unit — metres per second (m/s). For km/h: v [m/s] = v [km/h] / 3.6. For mph: v [m/s] = v [mph] × 0.44704. For knots: v [m/s] = v [kn] × 0.514444. For Mach: v [m/s] = v [Mach] × 343 (speed of sound at sea level, 20°C).

Example calculation

100 km/h equals 27.78 m/s, 62.14 mph, 53.99 knots and Mach 0.082. The speed of sound (Mach 1 = 343 m/s) equals 1234.8 km/h, 767.27 mph or 666.74 knots.

Frequently asked questions

How do I convert km/h to m/s?

Divide the km/h value by 3.6. For example, 90 km/h ÷ 3.6 = 25 m/s. The formula is v [m/s] = v [km/h] / 3.6.

What is a knot and where is it used?

A knot is one nautical mile per hour (1 kn ≈ 1.852 km/h ≈ 0.5144 m/s). It is the standard speed unit in maritime and aviation navigation.

What is Mach number and how is it calculated?

Mach number is the ratio of an object's speed to the speed of sound. At sea level, 20°C, Mach 1 = 343 m/s = 1234.8 km/h = 667 knots.

Multiply the mph value by 1.60934. For example, 60 mph × 1.60934 ≈ 96.56 km/h.

At sea level and 20°C, the speed of sound is about 343 m/s, which equals 1234.8 km/h or 667.1 knots.

Road speeds use km/h (Europe) or mph (USA, UK). Aviation and shipping use knots. Science uses m/s. Supersonic speeds are expressed in Mach.

Multiply the m/s value by 3.6. For example, 10 m/s × 3.6 = 36 km/h.

Instantaneous speed is speed at a given moment (e.g., a speedometer reading), while average speed is total distance divided by total time. This converter works with instantaneous speed values.

1 knot = 1 nautical mile/h = 1.852 km/h = 0.5144 m/s. A ship doing 20 knots travels at 37.04 km/h or 10.29 m/s.

A typical commercial jet (Boeing 737, Airbus A320) cruises at about 850–900 km/h, roughly Mach 0.78–0.82. The Concorde flew above Mach 2 (over 2400 km/h).

Results are indicative. The Mach conversion uses a standard sea-level value of 343 m/s; actual speed of sound varies with temperature and pressure. Not for navigational use.