Mach to Kilometers Per Hour (Ma to km/h)
1 Mach equals 1,225.0584 kilometers per hour exactly.
How to convert Mach to kilometers per hour
To convert Mach to kilometers per hour, multiply the number of Mach by 1,225.0584. This factor is exact. To go the other way, multiply kilometers per hour by 0.0008162876153 (rounded).
kilometers per hour = Mach × 1,225.0584
Example: 10 Mach = 12,250.584 kilometers per hour.
Approximate value. Standards for the Mach varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.
About these units
Mach (Ma)
The speed of sound at sea level in standard conditions (15 °C): about 340.294 m/s or 1,225 km/h. The speed of sound varies with temperature and altitude.
Ernst Mach, the Austrian physicist and philosopher born in Moravia in 1838, never defined a unit of speed, yet the ratio carries his name. In 1887 he and Peter Salcher presented a paper on photographing processes in air caused by projectiles, including a shadowgraph of the bow shock around a supersonic bullet fired from a Werndl carbine. The ratio of flow speed to the local speed of sound was later named for him.
Mach is therefore a dimensionless number, not a fixed speed, and because the speed of sound depends on temperature, so does Mach 1. It is about 340 m/s (1,225 km/h) in dry air at 15 °C at sea level, 343 m/s at 20 °C, and about 295 m/s above 11 kilometers where the air is cold. Flight is called subsonic below 0.8, transonic from 0.8 to 1.2, supersonic from 1.2 to 5 and hypersonic from 5 to 10. On 14 October 1947 Chuck Yeager flew the Bell X-1 to Mach 1.06, reported as 361 m/s.
1 Mach = 340.294 meters per second (approximately).
Sources: Wikipedia: Mach number; Wikipedia: Ernst Mach; Wikipedia: Speed of sound
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
Related conversions
- Kilometers per hour to Mach (reverse)
- Mach to meters per second
- Mach to miles per hour
- Mach to knots
- Mach to feet per second
- Mach to speed of light
- Meters per second to kilometers per hour
- Miles per hour to kilometers per hour
- Knots to kilometers per hour
- Feet per second to kilometers per hour
- Speed of light to kilometers per hour
- Centimeters per second to kilometers per hour
- Millimeters per second to kilometers per hour
- Kilometers per second to kilometers per hour
- Kilometers per minute to kilometers per hour
- Meters per minute to kilometers per hour
- Inches per second to kilometers per hour
- Feet per minute to kilometers per hour
See all speed units.