1 kilometer per hour (km/h or kph) = 0.539956803 knot (kn, kt or kts) = 0.621371192 miles per hour (mph) = 0.911344415 foot / second (ft/s) = 0.277777778 meters per second (m/s). The knot is a non-SI unit of speed. One knot is equal to one nautical mile per hour (1.852 km/h).