Speed Converter
mph, km/h, knots, meters per second and Mach number
About this tool
This free speed converter handles all common speed units: miles per hour (mph), kilometers per hour (km/h), knots (nautical miles per hour), meters per second (m/s), feet per second (ft/s), and Mach number. Enter any value and every other unit refreshes instantly, so you can see the full picture at a glance.
Key conversions and context: 1 mph = 1.60934 km/h. 1 knot = 1.852 km/h = 1.15078 mph (knots are used in aviation and maritime navigation because they tie directly to degrees of latitude — 1 nautical mile = 1 arc-minute). 1 Mach ≈ 343 m/s = 1,235 km/h at sea level at 20°C — the speed varies with air temperature and altitude, so Mach is always an approximation in everyday use. 1 m/s = 3.6 km/h.
When you need speed conversion: comparing US and European car speeds (US uses mph, most of the world uses km/h), reading wind speed in a weather report that uses knots vs. km/h, converting an aircraft's cruise speed from Mach 0.85 to km/h, or working through physics homework where answers are expected in m/s but given in mph.
Fun reference speeds: an Olympic sprinter runs about 10 m/s (36 km/h / 22 mph). A commercial jet cruises at around 900 km/h (560 mph / Mach 0.85). The speed of light is approximately 299,792 km/s — about 875,000 times faster than a jet. A category 5 hurricane exceeds 157 mph (252 km/h).