Mile per hour (mph)
The mile per hour, symbolized as mph, is an imperial unit that expresses speed in miles traveled per hour. It originated in England, where miles were the standard measure of distance, and gained prominence with the advent of road travel and railways. One mph equals 1.60934 kilometers per hour. The unit remains widely used in the United States, the UK, and a few other countries for road speed limits, automotive specifications, and aviation. Despite global metric adoption, mph persists in daily life and transportation, reflecting historical continuity and practical familiarity in imperial-system countries.
Kilometer per hour (km/h)
The kilometer per hour, symbol km/h, measures speed based on metric distance over time. It became widely used in Europe in the 19th century as road travel and railways expanded, providing a convenient unit for vehicle speed. One kilometer per hour equals 1000 meters traveled in one hour. Today, it is the standard speed unit for road traffic, navigation systems, and weather reporting in most countries, except a few that use miles per hour. Kilometers per hour offers an intuitive way to understand everyday speeds while maintaining metric consistency with distance and time measurements.