Pressure Altitude Calculator
Calculate pressure altitude from station pressure (aviation barometric formula).
About the Pressure Altitude Calculator
Pressure altitude is the altitude in the International Standard Atmosphere corresponding to a given pressure. Pilots use it for aircraft performance calculations.
$$ PA = (1 - (p/1013.25)^{0.190284})\times 145366.45\ \text{ft} $$
How to use
Enter the current station pressure (hPa), then click Calculate.
Worked example
At 1013.25 hPa → pressure altitude 0 ft (sea level).
How to use this calculator
- Enter the station pressure from your altimeter or weather source.
- Make sure the pressure is in a supported unit such as hPa or inHg.
- Click calculate to get the pressure altitude in feet.
- Review the step-by-step breakdown if you want to see how the result was computed.
The formula explained
$$ h_p = \left(1 - \left(\frac{p}{p_0}\right)^{0.190284}\right) \cdot 145366.45 $$
- \(h_p\) = pressure altitude
- \(p\) = station pressure
- \(p_0\) = standard sea level pressure, 1013.25 hPa or 29.92 inHg
- \(0.190284\) = constant from the standard atmosphere formula
- \(145366.45\) = conversion factor that turns the result into feet
Step by step method
- Start with the station pressure, which is the actual atmospheric pressure at your location.
- Compare it to standard sea level pressure used in aviation.
- Apply the aviation barometric formula to convert that pressure into altitude above the standard datum plane.
- Read the final pressure altitude result in feet.
Worked example
Suppose a pilot has a station pressure of 950.00 hPa at an airport and wants the pressure altitude.
- Use the formula \(h_p = \left(1 - \left(\frac{950.00}{1013.25}\right)^{0.190284}\right) \cdot 145366.45\).
- First compute the ratio: \(950.00 / 1013.25 \approx 0.93752\).
- Raise it to the power: \(0.93752^{0.190284} \approx 0.98775\).
- Finish the calculation: \(h_p \approx (1 - 0.98775) \cdot 145366.45 \approx 1779\) feet.
Answer. Pressure altitude is about 1,779 feet.
Tips and common mistakes
- Use the correct pressure reading, not altimeter setting, unless the tool specifically asks for that.
- Check the units before calculating, since hPa and inHg are not the same.
- Pressure altitude can be higher than field elevation on low-pressure days and lower on high-pressure days.
- Small input errors can change the result, so enter the pressure carefully.
Frequently asked questions
What is pressure altitude?+
The height above the standard 1013.25 hPa datum where that pressure occurs in the standard atmosphere.
Why do pilots use it?+
Aircraft engine and aerodynamic performance depend on air density, which tracks pressure altitude.
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