Speed Converter — Convert km/h, mph, m/s, Knots & More

Use this free speed converter to convert between kilometres per hour, miles per hour, metres per second, knots, feet per second and Mach. Type into any field for instant results across all speed units.

Speed Converter

Type in any field to convert all units instantly

🚀 Quick Reference

1 km/h0.621371 mph / 0.27778 m/s

1 mph1.60934 km/h / 0.44704 m/s

1 m/s3.6 km/h / 2.23694 mph

1 knot1.852 km/h / 1.15078 mph

Speed of light299,792,458 m/s

Speed of sound (air)343 m/s / 1,235 km/h

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Common Speed Units Explained

km/h — kilometres per hour, used for vehicle speeds in most countries.

mph — miles per hour, used in the US, UK and a few other countries.

m/s — metres per second, the SI unit of speed used in science and physics.

Knots — nautical miles per hour, used in aviation and maritime navigation.

Common Speed Conversions

1 km/h = 0.621371 mph. 1 mph = 1.60934 km/h. 1 m/s = 3.6 km/h = 2.237 mph. The speed of sound at sea level is approximately 343 m/s or 1,235 km/h.

What Is Mach Speed?

Mach is a unit of speed relative to the speed of sound. Mach 1 = the speed of sound (approximately 340 m/s at sea level). Mach 2 = twice the speed of sound. Aircraft that exceed Mach 1 are called supersonic.