Airspeed Conversion Calculator

Convert between IAS, CAS, TAS, and EAS based on standard atmosphere.

Airspeed Conversion Calculator (ISA Model)

IAS:
knots | m/s | mph | km/h
CAS:
knots | m/s | mph | km/h
TAS:
knots | m/s | mph | km/h
EAS:
knots | m/s | mph | km/h
Speed of Sound:
knots | m/s | mph | km/h
Mach Number:

Convert between Indicated Airspeed (IAS), Calibrated Airspeed (CAS), True Airspeed (TAS), and Equivalent Airspeed (EAS) in various units: knots, m/s, mph, and km/h. The calculator also computes Mach number and speed of sound for any given altitude.

The Airspeed Conversion Calculator is based on the ISA model, which assumes standard atmospheric conditions at any altitude. It does not take direct inputs for pressure and temperature. The ISA model provides standard conditions for air density and temperature at any altitude.

Airspeed Types

  • Indicated Airspeed (IAS): The speed shown on the aircraft’s pitot-static airspeed indicator.
  • Calibrated Airspeed (CAS): IAS corrected for instrument errors.
  • True Airspeed (TAS): The actual speed of the aircraft through the air, accounting for altitude and temperature.
  • Equivalent Airspeed (EAS): TAS corrected for compressibility effects, important at higher speeds and altitudes.

Formulas for Airspeed Conversions

  • Indicated Airspeed (IAS) to Other Airspeeds:
    • IAS to TAS: TAS = IAS * (ρ0/ρ)^(1/2)
    • IAS to EAS: EAS = IAS * (ρ0/ρ)^(1/2)
    • IAS to CAS: Typically, CAS is assumed to be equal to IAS unless there are significant instrument errors.
  • Calibrated Airspeed (CAS) to Other Airspeeds:
    • CAS to TAS: TAS = CAS * (ρ0/ρ)^(1/2)
    • CAS to EAS: EAS = CAS * (ρ0/ρ)^(1/2)
    • CAS to IAS: Typically, CAS is assumed to be equal to IAS unless there are significant instrument errors.
  • True Airspeed (TAS) to Other Airspeeds:
    • TAS to IAS: IAS = TAS * (ρ/ρ0)^(1/2)
    • TAS to CAS: CAS = TAS * (ρ/ρ0)^(1/2)
    • TAS to EAS: EAS = TAS
  • Equivalent Airspeed (EAS) to Other Airspeeds:
    • EAS to IAS: IAS = EAS * (ρ/ρ0)^(1/2)
    • EAS to CAS: CAS = EAS * (ρ/ρ0)^(1/2)
    • EAS to TAS: TAS = EAS
  • Note:
    • ρ0 is the standard sea level air density (approximately 1.225 kg/m³).
    • ρ is the actual air density at the aircraft’s altitude.
    • EAS is essentially the TAS corrected for compressibility effects.