Calculate pressure altitude from field elevation and altimeter setting. Essential for performance charts, density altitude, and flight planning.
Airport or field elevation above mean sea level
Current altimeter setting (standard: 29.92")
Formula
PA = 0 + (29.92 − 29.92) × 1,000
PA = 0 + (0.00) × 1,000
PA = 0 + 0
Pressure Altitude
0
feet
Correction
+0
ft from field elev.
ISA Temp
15.0
°C at this PA
At standard pressure (29.92" Hg), pressure altitude equals field elevation.
The needle rotates based on deviation from standard pressure (29.92" Hg). An altimeter setting at standard shows no correction needed.
| Altimeter Setting (inHg) | Correction to Field Elev. | Effect |
|---|---|---|
| 30.92" | -1,000 ft | PA lower than field |
| 30.42" | -500 ft | PA lower than field |
| 30.12" | -200 ft | PA lower than field |
| 29.92" | 0 ft (standard) | PA equals field elevation |
| 29.72" | +200 ft | PA higher than field |
| 29.42" | +500 ft | PA higher than field |
| 28.92" | +1,000 ft | PA higher than field |
Rule of thumb: For every 0.01" Hg below 29.92, add ~10 ft to field elevation. For every 0.01" above 29.92, subtract ~10 ft.
Pressure altitude is the altitude indicated when the altimeter is set to the standard datum plane of 29.92 inches of mercury (1013.25 hPa). It represents the height above the standard datum plane and is used as a reference for aircraft performance calculations, airspace transitions, and flight level assignments above 18,000 ft MSL.
The standard formula used in aviation:
Pressure Altitude = Field Elevation + (29.92 - Altimeter Setting) × 1,000This formula is based on the fact that pressure decreases by approximately 1 inch of mercury for every 1,000 feet of altitude gain in the lower atmosphere. When the altimeter setting is below 29.92, the air pressure is lower than standard, so the pressure altitude is higher than the field elevation (the aircraft “thinks” it is higher).
Every Pilot's Operating Handbook (POH) uses pressure altitude as the primary input for takeoff distance, landing distance, climb rate, and cruise performance charts. Using field elevation instead of pressure altitude on a low-pressure day can lead to underestimating the required runway length, especially at high altitude airports.
Pressure altitude is the starting point for calculating density altitude, which corrects pressure altitude for non-standard temperature. Density altitude determines true aircraft performance and is the single most important altitude for takeoff and landing calculations on hot days or at high elevation airports.
FAR 91.211 requires supplemental oxygen based on cabin pressure altitude: above 12,500 ft for more than 30 minutes, required above 14,000 ft, and passengers must be provided oxygen above 15,000 ft. Above 18,000 ft MSL (FL180), all aircraft must set altimeters to 29.92 and fly pressure altitude (flight levels).
This classic aviation mnemonic reminds pilots that flying from an area of high pressure to low pressure (without adjusting the altimeter) causes the altimeter to read higher than the actual altitude. In other words, the aircraft is lower than the pilot thinks, creating terrain clearance risk. Always get the current altimeter setting from ATIS, ASOS, or ATC.
Pressure altitude questions appear on every FAA knowledge test — PPL, Instrument, Commercial, and Part 107.
Sample FAA Question
What is the pressure altitude at an airport with a field elevation of 3,000 ft MSL if the altimeter setting is 29.82 inHg?
Practice thousands of questions just like this one. Performance calculations, weather, regulations, and more.