True Airspeed Calculator
TAS ≈ IAS · sqrt(ρ₀/ρ)
How to Use This Calculator
1
Enter IAS
Indicated airspeed from instruments.
2
Enter Pressure Altitude
From altimeter set to 29.92 inHg.
3
Enter OAT
Outside air temperature in °C.
Formula
TAS ≈ IAS · √(ρ₀/ρ)
ρ = p/(R·T), p = p₀·(1 − L·h/T₀)^(gM/(RL))
Note: Approximates CAS≈IAS and neglects compressibility/position errors.
About TAS
True airspeed increases with altitude and temperature for a constant IAS because air density decreases.
Frequently Asked Questions
How does wind affect TAS?
It doesn’t. Wind affects ground speed, not true airspeed.
Is CAS the same as IAS?
They differ slightly; for simplicity this tool treats IAS≈CAS.