Calculators / Atmosphere & Weather / Mach Number

Verify before flight. Check the POH/AFM for aircraft-specific limits and performance.

Atmosphere & Weather

Mach Number Calculator

Estimate Mach number from true airspeed and outside air temperature, including the local speed of sound.

True airspeed

Temperature

°C

Mach—

Local speed of sound—

TAS—

450 kt TAS at −50°C

At −50°C, the model gives a local speed of sound of about 582.1 kt. A TAS of 450 kt is 450 / 582.1 ≈ Mach 0.773.

Use true airspeed and local temperature. Dividing indicated airspeed by the sea-level speed of sound does not give the same result.

Mach number = true airspeed ÷ local speed of sound, with local sound speed calculated from temperature.