Density altitude calculator

The altitude in the standard atmosphere at which the air would be as thin as it is now. The wings, propeller and engine perform as if the aircraft were at that height, so a hot day at a high airfield can feel thousands of feet higher than the elevation on the chart.

First find the pressure altitude: the elevation corrected for the day's pressure, about 30 ft for every hectopascal below 1013. Then correct it for temperature: about 120 ft for every degree Celsius above the standard temperature at that altitude. The calculator uses the full standard atmosphere formulas rather than the rules of thumb.

Pressure altitude corrects only for pressure; it is what the altimeter reads set to 1013 hPa (29.92 inHg). Density altitude corrects for temperature as well, and it is the one that decides performance.

The engine makes less power, the propeller less thrust, and the wing needs a higher true airspeed to lift the same weight. Take-off runs get longer and climb rates drop, which is how density altitude catches pilots out at short or high airfields on warm days.

Yes, slightly: moist air is less dense than dry air. The effect is usually a few hundred feet at most, so the calculator leaves it out, as most flight manual charts do.

Yes. It is free for any pilot, with nothing to sign up for, and nothing you enter leaves your browser unless you save it to a flight plan.