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.

Indicated altitude (ft)

Indicated altitude.

OAT (°C)

Actual outside air temperature.

ISA temperature (°C)

ISA standard temperature at this altitude.

Correct an indicated altitude for the temperature deviation from ISA. 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]

True altitude (ft)

Temperature-corrected (true) altitude.

• 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.

• ISA Deviation Calculator

  Compute how much the outside air temperature deviates from ISA at the altitude.

• ISA Deviation Calculator

  Compare the outside air temperature with the ISA standard temperature at a pressure altitude.

• Cold Temperature Correction Calculator

  Estimate the altitude correction for cold temperatures against the ISA atmosphere.