Calculate true airspeed using calibrated airspeed, pressure altitude, and outside air temperature. This free aviation calculator helps pilots estimate actual speed through the air for planning and navigation.
Enter calibrated airspeed, pressure altitude, and outside air temperature to estimate true airspeed in knots.
This calculator estimates true airspeed from calibrated airspeed by adjusting for changing air density. Air density depends on pressure altitude and outside air temperature.
This gives a more useful estimate than a simple 2 percent per thousand feet rule of thumb.
True airspeed is the aircraft’s actual speed through the surrounding air mass. Unlike indicated or calibrated airspeed, true airspeed changes as altitude and temperature change because air density changes.
At higher altitudes, the air is less dense, so true airspeed is usually higher than calibrated airspeed for the same indicated aerodynamic condition. That is why pilots use true airspeed in navigation, flight planning, and groundspeed estimation.
No. True airspeed is speed through the air. Groundspeed is speed over the ground after wind is factored in.
As altitude increases, air density decreases. For the same indicated aerodynamic effect, the aircraft must move faster through the thinner air.
Calibrated airspeed is more accurate because it corrects indicated airspeed for instrument and position error. For many training uses, pilots sometimes approximate with IAS if CAS is not available.
This calculator provides a practical planning estimate. For aircraft-specific performance and certified data, always use your POH, AFM, or approved avionics sources.