Speed Converter
Convert between different speed units — meters per second, kilometers per hour, miles per hour, knots, feet per second, and Mach number.
About Speed Converter
Our Speed Converter is a free online tool that instantly converts between common speed units used in science, aviation, maritime navigation, and everyday life. Whether you need to convert km/h to mph, knots to m/s, or understand Mach numbers, this tool provides accurate conversions with detailed results.
Speed is a measure of distance traveled per unit of time. Different fields use different units: meters per second is the SI unit used in physics and engineering, kilometers per hour and miles per hour are common for road speeds, knots are used in maritime and aviation contexts, and Mach number represents speed relative to the speed of sound.
This converter shows not only the direct conversion result but also all equivalent values across all supported units, plus the conversion factor used. This makes it easy to compare and understand speed measurements in any context.
Frequently Asked Questions
Q What is a knot and why is it used?
A knot is a unit of speed equal to one nautical mile per hour (approximately 1.852 km/h or 1.151 mph). It's used in maritime and aviation navigation because nautical miles are based on the Earth's circumference (1 nautical mile = 1 minute of latitude), making it convenient for chart-based navigation over water and through the air.
Q What does Mach number mean?
Mach number is the ratio of an object's speed to the speed of sound in the surrounding medium. Mach 1 equals the speed of sound (approximately 343 m/s or 1,235 km/h at sea level and 20°C). Mach numbers below 1 are subsonic, around 1 is transonic, and above 1 is supersonic. The speed of sound varies with temperature and altitude, so this converter uses the standard sea-level value.
Q How do I convert km/h to mph?
To convert km/h to mph, multiply by 0.621371. For example, 100 km/h = 62.14 mph. To convert mph to km/h, multiply by 1.60934. A quick mental shortcut: km/h is roughly 60% of mph value, so 100 km/h ≈ 60 mph (the exact answer is 62.14 mph). Our converter handles these calculations precisely for you.