Mach Number Calculator – from TAS & Temperature/Altitude
Quickly calculate Mach number using True Airspeed (TAS) and either air temperature or altitude.
Mach Number Calculator
What is Mach Number
The Mach number is a dimensionless quantity in fluid dynamics that compares the speed of an object (or a flow) to the local speed of sound in the same medium.
It’s defined as: M = u / c
Where:
- M = Mach number
- u = speed of the object or flow relative to the medium
- c = speed of sound in that medium (which depends on temperature and medium properties)
The speed of sound isn’t constant — in air at sea level, it’s about 343 m/s (1,235 km/h) at 20 °C, but it changes with temperature and medium. For example, sound travels faster in water and even faster in steel. Under standard atmospheric conditions (ISA), it decreases with altitude because temperature drops as you climb.
How to Interpret Mach Numbers
| Mach Range | Name | Description |
|---|---|---|
| M < 0.8 | Subsonic | Slower than sound; typical for most commercial aircraft |
| 0.8 – 1.3 | Transonic | Near the speed of sound; shock waves begin to form |
| M = 1 | Sonic | Exactly at the speed of sound |
| 1.3 – 5 | Supersonic | Faster than sound; used by fighter jets and Concorde |
| 5 – 10 | Hypersonic | Extremely fast; experimental aircraft, re-entry vehicles |
| > 10 | High-hypersonic / Hypervelocity | Rare, mostly in space research |