Pressure Altitude Calculator
Enter the field elevation and the current altimeter setting to get the pressure altitude, the altitude in the standard atmosphere that matches today's pressure. You can also start from a station pressure reading, and the page shows the rule-of-thumb check, station pressure, ISA temperature and a table for other altimeter settings.
Last updated:
from the METAR, ATIS or AWOS
actual pressure at the field, not corrected to sea level
How to use the Pressure Altitude Calculator
- Choose the method: altimeter setting from the METAR/ATIS, or a station pressure reading.
- Enter the field elevation in feet or meters (from the airport chart or diagram).
- Enter the altimeter setting in inHg or hPa, or the station pressure.
- Press Calculate to see the pressure altitude and the working.
- Use the result in your aircraft's performance charts, or continue to density altitude.
Pressure altitude formulas
- Rule of thumb (inHg):
PA = elevation + (29.92 − altimeter setting) × 1,000 ft - Rule of thumb (hPa):
PA ≈ elevation + (1013 − QNH) × 27 ft(many pilots round to 30 ft per hPa) - Station pressure from altimeter setting:
P = QNH × ((288.15 − 0.0065 h) ÷ 288.15)5.25588, h in meters - Exact pressure altitude:
PA = (1 − (P ÷ 1013.25)0.190284) × 145,366.45 ft
These come from the International Standard Atmosphere: 15 °C and 1013.25 hPa (29.92 inHg) at sea level, cooling 1.98 °C per 1,000 ft.
Pressure altitude table
| Field elevation ↓ / altimeter → | 29.42 | 29.67 | 29.92 | 30.17 | 30.42 |
|---|---|---|---|---|---|
| 0 ft | 467 ft | 233 ft | 1 ft | -229 ft | -458 ft |
| 2,000 ft | 2,459 ft | 2,229 ft | 2,000 ft | 1,773 ft | 1,547 ft |
| 5,000 ft | 5,448 ft | 5,223 ft | 4,999 ft | 4,777 ft | 4,556 ft |
| 8,000 ft | 8,438 ft | 8,217 ft | 7,998 ft | 7,780 ft | 7,564 ft |
Exact values from the formula above. Notice that each 0.25 inHg changes pressure altitude by about 220–230 ft, close to the 1,000 ft per inch rule of thumb.
Why pilots use pressure altitude
Takeoff distance, climb rate and engine power charts are drawn against pressure altitude and temperature, because together they define the air the wing and engine actually meet. It is also the reference for flight levels and for transponder altitude reporting (Mode C/S), which always encodes pressure altitude regardless of the local altimeter setting. Remember the saying "high to low, look out below": flying into lower pressure without resetting the altimeter makes it read higher than your true altitude.
Frequently asked questions
How do you calculate pressure altitude?
The quick method is pressure altitude = field elevation + (29.92 − altimeter setting) × 1,000 ft. For example, at 5,434 ft with 29.85 inHg it is about 5,434 + 70 = 5,504 ft. The exact method converts the altimeter setting to station pressure and uses PA = (1 − (P ÷ 1013.25)^0.190284) × 145,366.45 ft.
What is pressure altitude?
It is the height in the International Standard Atmosphere at which the pressure equals the pressure where you are. It is what an altimeter reads when set to 29.92 inHg (1013.25 hPa), and it is the starting point for aircraft performance charts and density altitude.
How do I calculate pressure altitude with hPa?
Each hPa below 1013 adds about 27 ft near sea level (some pilots use 30 ft): PA ≈ elevation + (1013 − QNH) × 27 ft. With QNH 1002 hPa at 450 m (1,476 ft) that gives about 1,780 ft. The calculator also applies the exact formula.
What is the difference between pressure altitude and density altitude?
Pressure altitude corrects only for non-standard pressure. Density altitude also corrects for non-standard temperature (and humidity), so it describes how the aircraft actually performs. On a hot day density altitude can be thousands of feet higher than pressure altitude.
Is pressure altitude the same as flight level?
Flight levels are pressure altitudes in hundreds of feet with the altimeter set to 29.92 inHg or 1013 hPa, used above the transition altitude (18,000 ft in the US). FL350 is a pressure altitude of 35,000 ft.
When is pressure altitude higher than field elevation?
Whenever the altimeter setting is below standard (29.92 inHg or 1013.25 hPa). Low pressure means the air at the field behaves like air higher up in the standard atmosphere. With a high altimeter setting, pressure altitude is below field elevation and can even be negative near sea level.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.