What density altitude means
Density altitude is the height in the standard atmosphere where the air would be as thin as the air at your field right now. Heat, humidity and low pressure all raise it. The wing makes less lift and a normally aspirated engine less power, so the takeoff roll gets longer and the climb gets weaker.
How it's worked out
The calculator follows the National Weather Service method. It turns the altimeter setting and field elevation into station pressure (or uses the station pressure you enter), works out pressure altitude from that, adds the effect of humidity through the dew point (virtual temperature), and then finds the density altitude. A relative humidity is turned into a dew point first. The 120 ft per degree rule of thumb sits next to it as a cross-check, never as the main answer.
The warning bands (3,000, 6,000 and 8,000 ft) are a plain-language guide chosen for this page, not an FAA standard. Your aircraft's own performance charts are the only numbers to plan with.
Guides
- Density altitude with humidity and dew point
- Density altitude chart by elevation and temperature
- The 120 ft per degree rule against the full formula
- Density altitude for long-range shooting
- Density altitude for drag racing
- Density altitude for drone pilots
Figures are estimates rounded to the nearest foot. Weather changes. Check the current report before every flight.