Conversion Table
Mach
to miles per hour Conversion Table: 
Ma to mph
1.0 = 761.2
2.0 = 1522.4
3.0 = 2283.6
4.0 = 3044.8
5.0 = 3806 
Mach
to miles per hour
6.0 = 4567.2
7.0 = 5328.4
8.0 = 6089.6
9.0 = 6850.8
10 = 7612 
miles per hour
to Mach Conversion Table: 
mph to Ma
1.0 = 0.00131
2.0 = 0.00263
3.0 = 0.00394
4.0 = 0.00525
5.0 = 0.00657

miles per hour to Mach
6.0 = 0.00788
7.0 = 0.00920
8.0 = 0.01051
9.0 = 0.01182
10 = 0.01314

Mach number (Ma or M) is the speed of an object moving in air, divided by the speed of sound at that particular conditions, including temperature and pressure. At Standard Sea Level and temperature 15 degrees Celsius, the speed of sound is 761.2 miles per hour (mph) = 340.3 meters per second (m/s) = 1225 kph = 1116 foot per second (ft/s) = 661.5 knots (kn, kt or kts). The speed of sound is equal to 678 mph at temperature 48 degrees F and altitude 30000 feet . 