Kilometers per Hour (km/h)
Kilometers per hour (km/h) measures speed as the number of kilometers traveled in one hour. It converts directly to meters per second by multiplying by 1000/3600. This unit is standardized internationally for expressing road and vehicle speeds [bipm-si-brochure].
Origin
The kilometer per hour unit was adopted alongside the metric system in the 19th century, formalized by the International System of Units (SI) established by the BIPM. It became widespread for transportation speed limits due to metrication efforts in Europe and worldwide [bipm-si-brochure].
Worldwide Use
Kilometers per hour is the standard speed measurement in most countries, including all European nations, Canada, Australia, and many others. It is used extensively in road traffic regulations, automotive industries, and international transportation standards [nist-si-guide].
Common References
- Typical city driving speed is about 50 km/h
- Highway speed limits often range from 90 to 130 km/h
- A commercial airplane taxiing on the runway moves at about 30 km/h
- A bicycle can reach speeds near 25 km/h on flat terrain