Enter the total number of in or mm of mercury (or millibars) into the calculator. The calculator will display the equivalent pressure altitude in ft or meters.

Pressure Altitude Formula

The following formula is used to convert mercury into altitude feet.

h(alt) = ( 1 – ( P / 1013.25) ^ .190284) * 145366.45

  • Where h(alt) is the altitude pressure (ft)
  • P is the measured pressure

Pressure Altitude Definition

Pressure altitude is a crucial concept for pilots and aviation enthusiasts as it provides a standardized reference point for measuring and comparing altitudes. It is a term used to describe the altitude of an aircraft above a specific pressure level rather than the distance above sea level.

Atmospheric pressure decreases as altitude increases, which affects the performance of aircraft and their systems. Pressure altitude is determined by calibrating the aircraft’s altimeter to a standard atmospheric pressure setting, typically 29.92 inches of mercury (inHg), known as the standard datum plane.

By using pressure altitude, pilots can assess their position relative to this standard reference level, regardless of variations in local atmospheric pressure.

Pressure Altitude Example

How to calculate altitude pressure

  1. First, measure the station pressure.

    This station pressure will normally be measured in mm or inches of mercury.

  2. Next, convert to pressure.

    Convert the pressure from mm or in of mercury to millibars.

  3. Calculate the altitude pressure.

    Using the pressure from step 2, calculate the pressure altitude using the formula above.


What is pressure altitude?

Pressure altitude is the equivalent height in the atmosphere one would travel in order to reach the pressure given.

pressure altitude calculator
pressure altitude formula