ISA Calculator

Enter one property to calculate the others based on the International Standard Atmosphere model. Note: Calculating from temperature is only valid in the Troposphere.

ISA Model Notes

  • Based on the ICAO Standard Atmosphere (1993).
  • Assumes dry air, constant gravity, and specific temperature profiles.
  • Troposphere: Linear temperature decrease up to 11 km (15.0°C at sea level to -56.5°C).
  • Lower Stratosphere: Isothermal layer (-56.5°C) from 11 km up to 20 km (calculations limited to 80km).
  • Sea Level Standards: 288.15 K (15.00 °C), 101325 Pa (1013.25 hPa).
  • Calculating altitude from temperature is only possible within the troposphere range (-56.5°C to 15.0°C).