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Density Altitude Calculator

Find the density altitude affecting aircraft performance.

Result

7,958 ft
5.10 °C

How it is calculated

Density altitude is the altitude in the standard atmosphere that has the same air density as the current conditions. The tool uses a common approximation. First the standard (ISA) temperature at your pressure altitude: TISA = 15 − 1.98 × PA ÷ 1000. Then DA = PA + 118.8 × (OAT − TISA). PA is pressure altitude in feet, OAT is outside air temperature in °C. Hot air is thinner, so DA rises when OAT is above ISA. Results are shown as feet (rounded to a whole number) and the ISA temperature in °C. Humidity is not considered, and the approximation is best at moderate altitudes.

Worked example

An airfield has a pressure altitude of 5,000 ft and the outside temperature is 30 °C. The ISA temperature there is 15 − 1.98 × 5 = 5.10 °C. The temperature is 24.9 °C above standard. Multiply 24.9 by 118.8 to get about 2,958 ft and add the pressure altitude: the density altitude is 7,958 ft. The aircraft performs as if the airport were almost 3,000 ft higher.

Try this example →

Common mistakes

  • Using field elevation instead of pressure altitude. Pressure altitude is read with the altimeter set to 1013.25 hPa (29.92 inHg), and the two differ when pressure is not standard.
  • Entering the temperature in Fahrenheit. The tool expects °C.
  • Entering altitude in metres. The formula and the result are in feet.
  • Assuming a cold day gives a higher density altitude. Below ISA temperature the result is lower than the pressure altitude.
  • Treating the result as exact for performance planning. The pilot's operating handbook charts take precedence over this approximation.

About this calculator

This calculator finds density altitude — the altitude in standard atmospheric conditions that corresponds to the air's actual density — from pressure altitude and outside air temperature, using the approximation DA = PA + 120 × (OAT − ISA temperature at that altitude).

Pilots use it before takeoff, especially at high-elevation or hot-weather airports, because lower air density (higher density altitude) reduces engine power, propeller efficiency, and wing lift, lengthening takeoff rolls and reducing climb performance. Enter your pressure altitude and outside air temperature to see the density altitude affecting your aircraft's performance.

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