Weather / Aviation
Density Altitude Calculator
Work out density altitude for an airfield from its elevation, the altimeter setting, the temperature, and optionally the dew point, with the pressure altitude and ISA deviation.
Density Altitude Calculator: The calculator finds the pressure altitude from the elevation and altimeter setting, then the air density from the pressure, temperature, and the moisture given by the dew point, and finally the altitude in the International Standard Atmosphere with the same density. Its results match the MetPy library's standard-atmosphere functions within a few feet. At a 5,000 ft field on a 30 °C day with standard pressure, the density altitude is about 7,800 ft. Runs 100% locally in your browser with zero server file uploads.
- Category
- Everyday tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
The aircraft will perform as if 2,801 ft higher than the field: longer take-off run and slower climb. Check the performance charts.
Density altitude is the altitude in the standard atmosphere with the same air density, found here from the pressure altitude, temperature, and, if given, the dew point (moist air is less dense). For planning only: use your aircraft's documents and approved tools for flight decisions.
Hot, high, and humid
Density altitude rises by roughly 120 ft for every degree Celsius above the standard temperature, and the standard temperature itself falls by about 2 °C per 1,000 ft. A field at 5,000 ft has a standard temperature of 5 °C, so a 30 °C afternoon there puts the density altitude near 7,800 ft.
The dew point can be found from temperature and humidity with the dew point calculator.
Pressure altitude
Pressure altitude is the altitude an altimeter reads when set to 1013.25 hPa (29.92 inHg). It rises about 27 ft for each hectopascal (1,000 ft per inch of mercury) that the altimeter setting falls below standard, so low pressure also raises the density altitude.
How to use it
- Enter the field elevation in feet and the altimeter setting (QNH) in hPa or inHg.
- Enter the outside air temperature, and the dew point if you have it.
- Read the density altitude and compare it with your aircraft's performance charts.
Privacy & limitations
Everything is worked out in your browser.
Related tools
Frequently asked questions
Why does density altitude matter?
Engines, propellers, and wings all perform according to air density, so on a hot day at a high field an aircraft takes off and climbs as if it were thousands of feet higher.
Do I need the dew point?
It is optional: humid air is slightly less dense than dry air, typically adding a few hundred feet on a warm, humid day. Without it, the air is taken as dry, as most flight computers do.
Can I use this for flight planning?
As a cross-check only; use your aircraft's flight manual and approved tools for performance decisions.
Free tool · runs in your browser · no account required