Use this calculator for flight-planning study or a first-pass cross-check when all inputs describe the same aircraft, atmospheric condition, and phase of flight.

TAS (kt)

True airspeed.

Pressure altitude (ft)

Pressure altitude of the observation in the standard atmosphere.

Convert true airspeed to equivalent airspeed for the altitude's density ratio. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

EAS (kt)

Equivalent airspeed at sea level density.

• Do not use a generic calculator in place of the current aircraft flight manual, approved performance data, operating limitations, NOTAMs, weather, or regulations. Real performance changes with configuration, runway condition, altitude, temperature, wind, loading, and technique.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Cross-check the result against the aircraft flight manual or approved planning system, then apply the required safety margins. Keep signed wind, heading, altitude, speed, and fuel conventions explicit.

• Calibrated Airspeed Calculator

  Convert true airspeed back to calibrated airspeed using the two-percent-per-thousand-feet rule.

• CAS from EAS Calculator

  Convert equivalent airspeed to calibrated airspeed through the compressible Rayleigh pitot relation.

• Crossover Altitude Calculator

  Find by bisection the altitude where a constant Mach number and a constant calibrated airspeed correspond to the same true airspeed.