Miles per hour (mph) is the standard speed unit in the United States, United Kingdom, and a few other countries, used for speed limits, vehicle speedometers, and weather forecasts. American road signs exclusively display speed limits in mph, and car enthusiasts commonly reference 0-60 mph times as a performance benchmark. One mile per hour equals exactly 1.60934 kilometers per hour.

The knot (kn) equals one nautical mile per hour or approximately 1.852 kilometers per hour, the universal speed unit for maritime and aviation navigation. Ship speeds, aircraft velocities, and wind speeds in meteorological reports all use knots as their standard measurement. One knot equals exactly 1.15078 miles per hour, reflecting the longer nautical mile compared to the statute mile.