ISA Temperature at Altitude Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026The reference every pilot compares actual conditions against
The International Standard Atmosphere defines a reference temperature profile - 15C at sea level, cooling at a steady rate through the troposphere - letting pilots describe actual conditions as warmer or cooler "than standard" rather than comparing raw temperatures alone.
Worked example
For 10,000 feet:
ISA Temp = 15 - (1.98 x (10000/1000)) = -4.8 C
This result matches the real, published ISA standard atmosphere table value for 10,000 feet exactly - a useful confirmation of the formula, and a reminder of how quickly standard temperature drops with altitude even in ordinary flight conditions.