True Airspeed (TAS) Calculator

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Calibrated airspeed (CAS), also called rectified airspeed. For light general-aviation aircraft below 200 kts, you can use indicated airspeed (IAS) directly here with minimal error.
kts
Pressure altitude is your altimeter reading with the Kollsman window set to 29.92 inHg (1013.25 hPa). For flight-level entries (e.g., FL350) use 35,000 ft.
ft
Select "ISA standard" to use the model atmosphere temperature at your altitude, or enter your actual outside air temperature (OAT) from the aircraft instruments for a more accurate result.
True Airspeed (TAS)Subsonic (compressible)
288.7

Actual speed of the aircraft relative to the surrounding air mass

Equivalent Airspeed (EAS)248.1
Mach Number0.452
Local Speed of Sound638.3
Density Altitude10,001
TAS (knots)288.7
ISA Temperature Deviation0
0.452
Low subsonic<0.3Subsonic0.3-0.75High subsonic0.75-0.9Transonic0.9-1Supersonic1+

True Airspeed is 288.7 knots (Mach 0.452).

  • Your TAS is +15% above your CAS - this is the density effect of altitude on airspeed indication.
  • Density altitude is 10001 ft. Aircraft performance (takeoff roll, climb rate) is based on density altitude, not pressure altitude.
  • Temperature is ISA +0.0 degC. Warmer air reduces air density, increasing TAS and density altitude for the same pressure altitude.
  • At Mach 0.45, compressibility effects are significant. Using the simple rule-of-thumb (2% per 1,000 ft) would underestimate TAS.

Next stepAt these speeds, use EAS for structural load calculations and TAS for navigation and fuel flow planning.

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