Kilometer Per Hour (km/h)

Metric (SI)Current unit

The standard unit for road speeds in most countries: 1 km/h is about 0.2778 m/s.

1 kilometer per hour = 0.2777777778 meters per second (approximately).

About the kilometer per hour

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.

Sources: Wikipedia: Kilometres per hour; NIST Guide to the SI, Appendix B.8: conversion factors

Kilometer Per Hour conversion chart

1 kilometer per hour expressed in every other speed unit:

More Metric (SI) units

• meter per second (speed)
• centimeter per second (speed)
• millimeter per second (speed)
• kilometer per minute (speed)
• meter per minute (speed)
• meter (length)
• kilometer (length)
• centimeter (length)
• millimeter (length)
• micrometer (length)
• nanometer (length)
• picometer (length)
• decimeter (length)
• hectometer (length)
• decameter (length)
• kilogram (weight & mass)

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