Altitude Calculator

Calculating Pressure and Density Altitude

Calculating Pressure and Density Altitude is a fundamental skill for safe flight operations. Aircraft performance—including takeoff distance, rate of climb, and engine power—is directly dependent on the density of the air.

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Pressure Altitude (PA) is a baseline calculation. It is the altitude shown on an altimeter when the pressure is set to the standard datum of 1013.25 hPa. It is the first step required to calculate your aircraft's performance.

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Density Altitude (DA) is the most critical number for performance. It is the Pressure Altitude corrected for non-standard temperature. This is the altitude the aircraft "feels" like it is at. A high density altitude (common on hot days) means the air is thin, which will significantly reduce engine power, propeller thrust, and wing lift.

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This simple tool helps you instantly calculate both values, giving you a clear picture of the air density and its impact on your aircraft's expected performance.

How to use the Calculator

Using the tool is straightforward. Simply input the current atmospheric conditions for your airfield:
 

1. Step 1: Airfield Elevation (feet): Enter your airport's field elevation in feet, as found on your aeronautical chart.
    

2. Step 2: Altimeter Setting (hPa): Input the current altimeter setting (QNH) in hectopascals (hPa), as you would find on a METAR or ATIS broadcast.
    

3. Step 3: OAT (°C): Enter the current Outside Air Temperature in degrees Celsius (°C).
    

The calculator will instantly compute and display the precise Pressure Altitude and Density Altitude for your conditions. Pay close attention to the Density Altitude, especially if it is much higher than your field elevation.