Kilometers Per Hour to Miles Per Hour (km/h to mph)
1 kilometer per hour equals 0.6213711922 miles per hour (rounded).
How to convert kilometers per hour to miles per hour
To convert kilometers per hour to miles per hour, multiply the number of kilometers per hour by 0.6213711922. The factor is rounded to 10 significant digits. To go the other way, multiply miles per hour by 1.609344.
miles per hour = kilometers per hour × 0.6213711922
Example: 10 kilometers per hour = 6.213711922 miles per hour.
About these units
Kilometer Per Hour (km/h)
The standard unit for road speeds in most countries: 1 km/h is about 0.2778 m/s.
Myriameters per hour came first, at least in French. Although the meter was defined in 1799, speeds were initially quoted using the myriameter of 10,000 meters, and the phrase myriamètres par heure appears in 1802. The Dutch adopted the kilometer in 1817 under the name mijl. English abbreviations only appeared in the late nineteenth century, and many competing forms followed, from k. p. h. in 1889 to KMPH in 1940. Reuters and The Economist still prefer kph.
SI treats km/h as a unit symbol, not an abbreviation, and it is the generally preferred form. The European Union required SI usage in 1972, and a 1975 directive requires km/h on speedometers in all languages. In the United States a 1988 NHTSA rule allowed km/h on speedometers. Exactly 3.6 km/h make 1 m/s, one mile per hour is exactly 1.609344 km/h, and one knot is exactly 1.852 km/h. Road signs and speed limits in most of the world use it.
1 kilometer per hour = 0.2777777778 meters per second (approximately).
Sources: Wikipedia: Kilometres per hour; NIST Guide to the SI, Appendix B.8: conversion factors
Mile Per Hour (mph)
Exactly 0.44704 m/s. The unit for road speeds in the US, UK and a few other countries.
Early British motoring law is the best window into this unit. The 1861 Locomotive Act set a limit of 10 mph for light locomotives. The 1865 Red Flag Act cut it to 4 mph in the country and 2 mph in towns, with a person walking ahead with a flag. The Locomotives on Highways Act of 1896 raised it to 14 mph, and the Motor Car Act of 1903 to 20 mph. In 1931 all limits for cars were abolished, and 30 mph in built-up areas returned in 1935.
The mile per hour combines the mile, set at 5,280 feet in Elizabeth I's reign, with the hour, and it equals exactly 0.44704 m/s or 1.609344 km/h. The United Kingdom and United States use it on roads, along with several smaller countries, mostly territories or former territories of those two, and the US, Canada and Ireland use it for rail. Sports such as cricket, tennis and baseball quote ball speeds in it. Aviation and shipping prefer knots, about 0.869 of one mph each.
1 mile per hour = 0.44704 meters per second (exactly).
Sources: Wikipedia: Miles per hour; Wikipedia: Speed limits in the United Kingdom; Wikipedia: Mile
Related conversions
- Miles per hour to kilometers per hour (reverse)
- Kilometers per hour to meters per second
- Kilometers per hour to knots
- Kilometers per hour to feet per second
- Kilometers per hour to Mach
- Kilometers per hour to speed of light
- Kilometers per hour to centimeters per second
- Kilometers per hour to millimeters per second
- Kilometers per hour to kilometers per second
- Kilometers per hour to kilometers per minute
- Kilometers per hour to meters per minute
- Kilometers per hour to inches per second
- Kilometers per hour to feet per minute
- Meters per second to miles per hour
- Knots to miles per hour
- Feet per second to miles per hour
- Mach to miles per hour
- Speed of light to miles per hour
- Centimeters per second to miles per hour
- Millimeters per second to miles per hour
- Kilometers per second to miles per hour
- Kilometers per minute to miles per hour
- Meters per minute to miles per hour
- Inches per second to miles per hour
- Feet per minute to miles per hour
See all speed units.