Pressure Altitude Calculator
Enter the field elevation and the altimeter setting to get the pressure altitude, or work backward to the indicated altitude or the air pressure at an altitude.
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The pressure altitude calculator turns a field elevation and an altimeter setting into the pressure altitude, the height in the standard atmosphere where the air pressure matches the field. Choose a mode from What do you want to find?, enter the numbers in feet or meters and inHg or hPa, and read the result. The same page also works in the other direction, giving the indicated altitude for a known pressure altitude and the standard pressure at any altitude in inHg, hPa, kPa and mmHg.
The exact result comes from the standard atmosphere, and the rule of thumb shown beside it lets you see how far the shortcut strays. The calculator is a planning aid. The aircraft flight manual decides which figures you use in flight.
How to use the pressure altitude calculator
- Open What do you want to find? and pick one of three modes: pressure altitude from field elevation, indicated altitude from pressure altitude, or air pressure at an altitude.
- In the first mode, enter the Field elevation and choose feet or meters as its unit.
- Enter the Altimeter setting and choose inHg or hPa (mb) as its unit. Standard sea level is 29.92 inHg, which equals 1013.25 hPa.
- Read Pressure altitude (exact). With meters selected, the result also shows meters. Compare it with the Rule: 29.92 minus setting, times 1,000 ft line and the Rule minus exact value line.
- For the second mode, enter the Pressure altitude and the altimeter setting to read the Indicated altitude, which is the altimeter reading at that setting.
- For the third mode, enter the Altitude in the standard atmosphere to read the pressure in inHg, hPa, kPa and mmHg, along with the pressure ratio, the standard temperature and the density ratio.
- Load a preset such as Metric example or Pressure at 8,000 ft to test the page against a known case.
- Open How it was calculated to see the formula with your numbers. Use Print / save result for a printed sheet, Copy link to copy the link, and Reset to start again.
How do I calculate pressure altitude?
Pressure altitude equals the field elevation plus a correction for the altimeter setting. The quick method is Rule: 29.92 minus setting, times 1,000 ft, added to the elevation. The exact method uses the standard atmosphere, so a 29.62 inHg setting on a 5,000 ft field gives 5,270 ft exact, against 5,300 ft from the rule.
The exact method uses the standard pressure law up to 36,089 ft, with 1 inHg equal to 33.86389 hPa. Pressure altitude is the altitude in the standard atmosphere that has the static pressure at the field, which is the altimeter setting times the standard pressure ratio at the field elevation.
What is the barometric pressure at 8,000 feet?
The standard atmosphere gives 22.22 inHg, or 752.6 hPa, at 8,000 feet. That is 75.26 kPa or 564.5 mmHg, with a standard temperature of -0.8 °C. The pressure ratio is 0.7428 of sea level, and the FAA table lists the same 22.22 inHg.
Standard values at other altitudes:
| Altitude | Pressure (inHg) | Pressure (hPa) | Temperature (°C) |
|---|---|---|---|
| 0 ft | 29.92 | 1,013.3 | 15.0 |
| 4,000 ft | 25.84 | 875.1 | 7.1 |
| 10,000 ft | 20.58 | 696.8 | -4.8 |
| 20,000 ft | 13.75 | 465.6 | -24.6 |
How do I convert inHg to feet of altitude?
The usual shortcut is 1 inHg for every 1,000 ft, and it is exact only at 29.92 inHg. In the standard atmosphere a 1 inHg change moves pressure altitude by about 913 ft at sea level, 881 ft at 5,000 ft, 862 ft at 8,000 ft and 850 ft at 10,000 ft.
The rule overstates the change, more so at higher fields and the further the setting is from 29.92. At 1,200 ft with 30.45 inHg the exact pressure altitude is 718 ft and the rule gives 670 ft, 48 ft lower.
How to find pressure altitude without an altimeter setting?
Set the altimeter to 29.92 inHg and read the altitude it shows, which is the pressure altitude. The calculator needs an altimeter setting to work out pressure altitude from a field elevation, so without a setting there is no calculation. If you only need pressure at a known altitude, use the third mode, Air pressure at an altitude.
The handbook gives three routes: set the altimeter to 29.92 and read it, apply the correction from its altimeter setting table to the indicated altitude, or use a flight computer.
Sources
FAA-H-8083-25B Pilot’s Handbook of Aeronautical Knowledge (2016), chapter 11, Figures 11-2 and 11-3; U.S. Standard Atmosphere 1976 (NASA-TM-X-74335) Table I; NIST SP 811 Appendix B.8. Checked October 2026.
Questions from readers
What is pressure altitude used for?
Pressure altitude is the basis for performance data and for flight levels above 18,000 ft in the United States. Density altitude starts from it, so the density altitude calculator takes pressure altitude and temperature as its inputs.
Is the 29.92 rule accurate?
It is exact only at 29.92 inHg. At 5,000 ft with 29.62 inHg the rule gives 5,300 ft against an exact 5,270 ft, and at 8,000 ft with 29.50 inHg it gives 8,420 ft against 8,370 ft. The gap widens as the setting moves away from 29.92.
What is the difference between pressure altitude and indicated altitude?
Pressure altitude is the height in the standard atmosphere that matches the air pressure. Indicated altitude is the reading the altimeter shows when it is set to the local setting. At 8,000 ft pressure altitude with 29.62 inHg, the indicated altitude is 7,735 ft.
Why is pressure altitude higher when the setting is lower?
A setting below 29.92 inHg means the air at the field is at lower pressure than standard, so the field sits higher in the standard atmosphere and pressure altitude exceeds elevation. At a sea-level field with a setting of 29.70 inHg, the handbook correction is 205 ft.
How do I use hPa or mb?
Select hPa (mb) as the unit of the altimeter setting. One hPa equals one mb, and 1 inHg equals 33.86389 hPa, so 1013.25 hPa and 29.92 inHg describe the same standard pressure. A METAR shows the setting as a Q group, such as Q1013, which is in hPa.
What is QNH?
QNH is the altimeter setting in hPa that makes the altimeter read field elevation on the ground. Enter it in the altimeter setting field with hPa selected.
Related tools
- Density altitude calculator: use it to turn pressure altitude and temperature into density altitude.
- Altimeter setting converter: use it to convert inHg, hPa, mmHg and kPa and see the effect of a setting change.
- True airspeed calculator: use it to find true airspeed from calibrated airspeed and pressure altitude.
- Mach number calculator: use it for Mach number and calibrated airspeed at a pressure altitude.
- Altitude and performance tools: use it to see every altitude and performance tool in one list.
- METAR decoder: use it to read the altimeter setting from a weather report.
- E6B flight computer: use it for other flight computer solutions.
- Weight and balance calculator: use it for loading, separate from altitude.