Calculate International Standard Atmosphere temperature using pressure altitude. This free aviation calculator helps pilots compare actual conditions to standard atmospheric conditions for planning and performance calculations.
Enter pressure altitude in feet to calculate the standard ISA temperature in degrees Celsius.
Below the tropopause, ISA temperature decreases by about 1.98°C per 1,000 feet of pressure altitude.
Above approximately 36,000 feet, standard temperature is treated as a constant value near -56.5°C in this calculator.
ISA temperature is the standard temperature at a given altitude according to the International Standard Atmosphere model. Pilots use it to compare actual weather conditions to standard atmospheric conditions.
ISA temperature is especially useful for density altitude calculations, aircraft performance planning, and understanding how nonstandard temperature affects operations.
Standard ISA temperature at sea level is 15°C.
Comparing outside air temperature to ISA helps pilots understand whether conditions are warmer or colder than standard, which directly affects aircraft performance.
Yes. ISA temperature is one of the values commonly used when estimating density altitude.
This calculator uses a standard approximation and applies a fixed standard temperature above the tropopause. It is excellent for training and planning, but always use approved references when required for operations.