Density Altitude Calculator
Density altitude from pressure altitude, temperature and optional dewpoint — runs in your browser.
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About Density Altitude Calculator
Density altitude is the altitude in the standard atmosphere at which the air would have the same density as the air you are actually flying in. On a hot day at a high airfield the air is thin, so the aircraft performs as if it were much higher: longer take-off roll, weaker climb and less engine power. This density altitude calculator works it out from pressure altitude, outside air temperature and, optionally, dewpoint.
It uses the International Standard Atmosphere (15 °C at sea level, cooling about 1.98 °C per 1000 ft) and the standard relation between pressure, temperature and density, the same approach the US National Weather Service publishes. If you enter a dewpoint it also accounts for humidity, since moist air is slightly less dense than dry air. It shows the ISA temperature for your pressure altitude and how far today is above or below standard. The calculation runs in your browser.
How to use
- Find your pressure altitude: set the altimeter to 29.92 inHg (1013 hPa) and read it, or correct field elevation for the current altimeter setting.
- Enter the outside air temperature in degrees Celsius.
- Optionally enter the dewpoint from the METAR to include the effect of humidity.
- Read the density altitude, the ISA temperature and the deviation from ISA.
- Use the density altitude with your aircraft performance charts, and cross-check against the POH.