Mach Number Calculator
Calculate Mach number and speed of sound at altitude.
Speed of Sound Reference
| Temperature | Speed of Sound |
|---|---|
| +15C (sea level std) | 661 kt |
| 0C | 643 kt |
| -20C | 620 kt |
| -40C | 597 kt |
| -56.5C (tropopause) | 573 kt |
About Mach Number
Mach number is the ratio of TAS to the local speed of sound. At high altitudes, temperature decreases, reducing the speed of sound, so the same TAS gives a higher Mach number.
Speed of Sound = 38.97 x sqrt(T in Kelvin) knots