Convert Mile/Hour (mi/h) to Mach (20°C, 1 atm) (Ma (20°C)) instantly.
About these units
Mile/Hour (mi/h)
The mile per hour represents the number of miles traveled in one hour and is commonly used in the United States, the UK (in road contexts), and several other countries with legacy imperial systems. mph is deeply woven into cultural habits: driver training, speed limits, vehicular performance, and even athletic achievements are often expressed in miles per hour. In science and engineering, however, mph is rarely used because the mile and hour are not SI units. Still, mph retains strong emotional and historical associations—for example, the significance of a car "breaking 200 mph" or the legendary "88 mph" in popular culture. It persists because measurement units often survive long after their historical origins fade.
Mach (20°C, 1 atm) (Ma (20°C))
At 20°C and 1 atmosphere, the speed of sound in air is about 343 m/s, making Mach 1 = 343 m/s under those conditions. Mach numbers classify aerodynamic regimes: Mach 0.3–0.8 (Subsonic), Mach 0.8–1.2 (Transonic), Mach 1–5 (Supersonic), Mach 5+ (Hypersonic). Temperature influences Mach speed significantly; colder air slows sound, while warmer air increases its speed. Aircraft design, jet engines, wind tunnels, aerospace testing, and atmospheric re-entry physics all rely heavily on Mach numbers referenced to standard conditions.