Enter a Mach number or a speed (mph, km/h, m/s, or knots) to convert to the other, with options to set the speed of sound by temperature or altitude.
Mach to Mph Formula
The following formulas convert between Mach and speed using the local speed of sound determined by the chosen environment.
v = M \times a \quad \text{where} \quad a=\sqrt{\gamma R T}- Standard sea-level (15°C) speed of sound: a ≈ 340.3 m/s ≈ 761.207 mph.
- Constants: γ = 1.4 (dry air), R = 287.05 J/(kg·K); temperature T in kelvin.
- Unit links: 1 m/s = 2.236936 mph; 1 km/h = 0.621371 mph; 1 kn = 1.150779 mph.
- ISA temperature model: -6.5 K/km to 11 km, then isothermal to 20 km.
Mach to Mph Conversion Table
| Mach | mph |
|---|---|
| 0.1 | 76.121 |
| 0.2 | 152.241 |
| 0.3 | 228.362 |
| 0.4 | 304.483 |
| 0.5 | 380.604 |
| 0.6 | 456.724 |
| 0.7 | 532.845 |
| 0.8 | 608.966 |
| 0.9 | 685.086 |
| 1 | 761.207 |
| 1.2 | 913.448 |
| 1.5 | 1,141.811 |
| 2 | 1,522.414 |
| 2.5 | 1,903.018 |
| 3 | 2,283.621 |
| 4 | 3,044.828 |
| 5 | 3,806.035 |
| * Assumes sea-level ISA at 15°C: Mach 1 ≈ 761.207 mph. | |
How do you convert Mach to mph? Multiply Mach by the local speed of sound in mph: mph = Mach × a_mph; at sea level (15°C), a_mph ≈ 761.207, so mph ≈ 761.207 × Mach.
How do you convert mph to Mach? Divide mph by the local speed of sound in mph: Mach = mph ÷ a_mph; choose Standard, Custom Temperature, or Altitude (ISA) to set a_mph.
Example Problem
Convert Mach 2.3 at sea level (15°C) to mph.
Use the sea‑level relation: mph = Mach × 761.207.
mph = 2.3 × 761.207 ≈ 1,750.776 mph