Kilometers Per Hour to Mach Number Conversion

Kilometers Per Hour

Kilometers per hour are a measurement of speed expressing the distance travelled in kilometers in one hour.

The kilometer per hour, or kilometre per hour, is an SI unit of speed in the metric system. Kilometers per hour can be abbreviated as km/h, and are also sometimes abbreviated as kph. For example, 1 kilometer per hour can be written as 1 km/h or 1 kph.

Kilometers per hour can be expressed using the formula:
v_km/s = d_kmt_hr

The velocity in kilometers per hour is equal to the distance in kilometers divided by time in hours.

Mach Number

Mach, sometimes also referred to as a Mach number, is the ratio of the speed of an object to the speed of sound.^[1]

Mach can be abbreviated as M, and is also sometimes abbreviated as Ma. For example, Mach 1 can be written as 1 M or 1 Ma.

Although Mach can be abbreviated M or Ma, the Mach number is typically expressed with the number after the unit name. For example, the expression Mach 3 is preferred rather than 3 Machs or 3 M.

The speed is classified as either subsonic, transonic, supersonic, or hypersonic depending on the Mach number.

Speed classifications for various mach numbers.

Speed Classification	Mach Number
Subsonic	Mach < 1.0
Transonic	Mach = 1.0
Supersonic	Mach > 1.0
Hypersonic	Mach > 5.0