Kilometers Per Hour to Millimeters Per Second (km/h to mm/s)
1 kilometer per hour equals 277.7777778 millimeters per second (rounded).
How to convert kilometers per hour to millimeters per second
To convert kilometers per hour to millimeters per second, multiply the number of kilometers per hour by 277.7777778. The factor is rounded to 10 significant digits. To go the other way, multiply millimeters per second by 0.0036.
millimeters per second = kilometers per hour × 277.7777778
Example: 10 kilometers per hour = 2,777.777778 millimeters per second.
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
Millimeter Per Second (mm/s)
One thousandth of a meter per second. Used for very slow motion.
Biology and glaciology supply good yardsticks for a millimeter per second. The fastest-swimming bacterium, Thiovulum majus, typically moves at about 0.6 mm/s, and the Jakobshavn Isbrae glacier was recorded flowing at about 0.4 mm/s in 2003. At that rate ice covers roughly 35 meters in a day, because 0.4 mm/s multiplied by 86,400 seconds is about 34.6 m.
Faster, but still slow, is the world record speed of a snail, set in the United Kingdom at 2.75 mm/s, which works out to about 9.9 meters per hour. A millimeter per second is 0.001 m/s, so one meter per second equals 1,000 mm/s. The unit suits slow mechanisms, where meters per second would give awkward decimals, and it sits one step below the centimeter per second in the metric ladder.
1 millimeter per second = 0.001 meters per second (exactly).
Sources: Wikipedia: Orders of magnitude (speed); Wikipedia: Metre per second
Related conversions
- Millimeters per second to kilometers per hour (reverse)
- Kilometers per hour to meters per second
- Kilometers per hour to miles per hour
- 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 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 millimeters per second
- Miles per hour to millimeters per second
- Knots to millimeters per second
See all speed units.