Aviation Calculators
Pressure altitude.
Pressure altitude is the altitude your altimeter would show if it were set to the standard 29.92 inHg (1013.25 hPa). Enter the field elevation, or your indicated altitude, and the altimeter setting to get it. Runs in your browser; nothing is sent or stored.
Planning aid, not for flight operations
This tool is for study, trip planning and curiosity. It is not approved flight-planning or performance data. For an actual flight, use the aircraft's approved Pilot's Operating Handbook or Aircraft Flight Manual, current weather and charts, and your own judgement as pilot in command. Results can differ from your aircraft's real figures.
Inputs
Result
Fill the form and press Calculate.
Worked example
The FAA handbook's density altitude sample uses a 5,883 ft airport with an altimeter setting of 30.10 inHg. A high setting means the pressure at the field is higher than standard, so the pressure altitude is lower than the elevation. This calculator gives 5,725 ft, a correction of -158 ft. The handbook reads a rounded −165 ft from its chart and gets 5,718 ft, within 7 ft of this result.
How it works
The altimeter setting is converted to hectopascals (1 inHg = 33.8639 hPa). With r = (setting ÷ 1013.25)0.190284 and H the altitude you entered, pressure altitude = H × r + 145,366.45 × (1 − r) feet. This is the International Standard Atmosphere relation behind the NWS pressure altitude calculator, applied to the altimeter setting at the altitude entered.
Setting the standard 29.92 inHg gives a correction of about zero. A setting above standard gives a pressure altitude below the elevation; a setting below standard gives a pressure altitude above it.
Sources (each opened 2026-10-08): FAA, Pilot's Handbook of Aeronautical Knowledge, Chapter 8: Flight Instruments; FAA, Pilot's Handbook of Aeronautical Knowledge, Chapter 11: Aircraft Performance; NWS El Paso, TX, Pressure Altitude calculator.
FAQ
What is pressure altitude?
The FAA handbook describes it as the altitude indicated when the altimeter is set to 29.92 inHg, the altitude in the standard atmosphere that corresponds to the sensed pressure. It is used to compute density altitude, true airspeed and other performance data.
How do I find pressure altitude quickly?
The FAA handbook gives a standard pressure lapse rate of about 1 inHg per 1,000 ft of altitude, so each 0.01 inHg between your setting and 29.92 is roughly 10 ft. This calculator uses the full standard-atmosphere formula instead, so the two can differ by a few feet.
Should I enter the field elevation or my indicated altitude?
On the ground, enter the field elevation (the altimeter setting is referenced to it). In flight, with the altimeter set to the local setting, enter the indicated altitude. Instrument error is not corrected.
Can I enter hectopascals?
Yes. Choose hPa (millibars) as the unit and enter the QNH. The standard value is 1013.25 hPa.
Why does 29.92 inHg not give exactly zero correction?
29.92 inHg equals 1013.21 hPa, which is 0.04 hPa below the standard 1013.25 hPa, so you will see a correction of about 1 ft near sea level.
Is this approved for flight planning?
No. It is a learning and planning aid. Use approved sources and your aircraft's flight manual for operations.