It is currently the unit used for speed limits, and speeds, on roads in the United Kingdom, United States and other nations. It is also used to express the speed of delivery of a ball in various sporting events, such as cricket, tennis, and baseball at the higher levels of competition. A common abbreviation is mph or MPH, although mi/h is sometimes used in technical publications.
In the International System of Units (SI), the unit of speed or velocity is m/s. Road traffic speeds, in most countries, are quoted in km/h. Nautical and aeronautical applications, however, favor the knot as a common unit of speed: one knot is one nautical mile per hour.
When converting miles per hour to another unit of measurement, or vice versa, it helps to know exactly how miles and hours are related to other units of distance and time, respectively. For example, 1 mile is equal to 5,280 feet, 1,760 yards, or 1,609.344 meters. Likewise, 1 hour is equal to 60 minutes, or 3,600 seconds.