Speed Converter

Convert between different units of speed and velocity.

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Common Speed Conversions

• 1 km/h ≈ 0.621371 mph
• 1 mph ≈ 1.60934 km/h
• 1 m/s = 3.6 km/h
• 1 knot ≈ 1.852 km/h
• 1 Mach ≈ 1,225 km/h (at sea level, 20°C)
• Speed of light ≈ 299,792,458 m/s

Reference Speeds

• Walking speed: ~5 km/h (3 mph)
• Running speed: ~15 km/h (9 mph)
• Highway speed limit: ~100-120 km/h (60-75 mph)
• Commercial airplane: ~900 km/h (560 mph)
• Speed of sound: ~1,225 km/h (761 mph) at sea level

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About Speed Measurement

Speed is the rate at which an object covers distance. It's calculated as distance traveled divided by time taken. Different fields use different units: km/h for road travel in most countries, mph in the US, knots for marine and air navigation, and m/s in scientific contexts.

Mach Number

Mach number is the ratio of an object's speed to the speed of sound. The speed of sound varies with temperature and altitude, but at sea level at 20°C it's approximately 343 m/s (1,225 km/h or 761 mph). Mach 1 is the speed of sound, Mach 2 is twice the speed of sound, and so on.

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