Convert Mile/Hour (mi/h) to Mach (SI Standard) (Ma) 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 (SI Standard) (Ma)
Mach is a dimensionless measure of speed relative to the speed of sound in a given medium. Mach 1 corresponds to the speed of sound, Mach 2 is twice that speed, and so on. Mach values change with temperature, atmospheric pressure, and altitude because the speed of sound changes with these conditions. Aircraft performance, supersonic flight, rocket design, and shockwave analysis all depend heavily on Mach numbers. Mach is more than just a speed measure—it categorizes aerodynamic regimes: Subsonic (Mach < 1), Transonic (Mach 0.8–1.2), Supersonic (Mach 1–5), Hypersonic (Mach > 5). Mach numbers therefore provide insight into aerodynamic behavior, not just velocity.