Kilometer per hour (km/h) - Unit Information & Conversion
What is a Kilometer per hour?
Definition
Kilometers per hour (km/h or kph) is a unit of speed expressing the number of kilometers traveled in one hour.
History
Kilometers per hour became a common unit of speed with the widespread adoption of the metric system for distance (kilometer) and the standard use of hours for time measurement, particularly following the advent of automobiles and trains where measuring such speeds became practical and necessary.
Common Uses
- Road Traffic: The most common unit for speed limits and vehicle speeds (speedometers) worldwide, except in countries like the US and UK.
- Meteorology: Often used in public weather forecasts to report wind speeds, especially in metric countries.
- Navigation: Used alongside other units like knots in some aviation and maritime contexts, although less common than knots for primary navigation.
- Sports: Sometimes used to describe speeds in cycling, skiing, or running over longer distances.
Unit FAQs
Where is km/h primarily used?
Kilometers per hour is the standard unit for road speed in most countries around the world that use the metric system.
Is km/h an SI unit?
While it uses SI units (kilometer and hour derived from second), the official SI unit for speed is meters per second (m/s). However, km/h is accepted for use with SI.
How do you convert km/h to mph?
To approximate, divide the speed in km/h by 1.609. So, 100 km/h is roughly 62 mph. (1 km/h ≈ 0.621371 mph).
How do you convert km/h to m/s?
Divide the speed in km/h by 3.6. So, 100 km/h is approximately 27.78 m/s.
Kilometer per hour Conversion Formulas
To Meter per second:
To Mile per hour:
To Foot per second:
To Knot:
To Mach number:
To Speed of light:
Convert Kilometer per hour
Need to convert Kilometer per hour to other speed units? Use our conversion tool.