How it works
Convert speeds between miles per hour, kilometers per hour, meters per second, feet per second, knots, Mach number and the speed of light.
A knot is one nautical mile (exactly 1,852 m) per hour and is used for aircraft, ships and wind speed. Mach is the ratio to the speed of sound, which depends on air temperature; this converter uses the standard sea-level value of 340.294 m/s at 15 °C. At cruising altitude, where the air is colder, Mach 1 is about 295 m/s.
Formula
Result = value × (m/s per from-unit) ÷ (m/s per to-unit). 1 mph = 0.44704 m/s; 1 km/h = 1/3.6 m/s.
Questions people ask
How do I convert mph to km/h?
Multiply by 1.609344. For example, 60 mph is about 96.56 km/h. To go from km/h to mph, divide by 1.609344 (or multiply by about 0.621371).
How fast is a knot?
One knot is about 1.15078 mph or exactly 1.852 km/h.
How fast is Mach 1?
About 761 mph (1,225 km/h) at sea level in standard conditions. It is slower at high altitude because the speed of sound falls with temperature.