Calculator Inputs
Example Data Table
| Scenario | Station Pressure (hPa) | Altimeter (inHg) | Field Elevation (ft) | Altimeter-based Pressure Altitude (ft) | Station-pressure Altitude (ft) |
|---|---|---|---|---|---|
| Sea Level Field | 1,013.25 | 29.92 | 0.00 | 0.00 | 0.01 |
| Regional Strip | 995.00 | 29.38 | 850.00 | 1,390.00 | 501.89 |
| Mesa Airport | 930.00 | 28.92 | 4,200.00 | 5,200.00 | 2,352.24 |
| Cold Valley | 980.00 | 29.55 | 1,350.00 | 1,720.00 | 920.01 |
| High Plateau | 850.00 | 28.30 | 6,200.00 | 7,820.00 | 4,779.20 |
Formula Used
This calculator supports three related altitude methods, so you can compare aviation and atmospheric interpretations side by side.
Pressure Altitude (altimeter method) = Field Elevation + (29.92 − Altimeter Setting in inHg) × 1000
This is the common aviation shortcut used to convert an altimeter setting and known field elevation into pressure altitude.
Pressure Altitude (station pressure method) = 145366.45 × [1 − (Station Pressure in inHg / 29.92126)^0.190284]
This method derives altitude directly from measured station pressure under ISA assumptions.
Barometric Altitude = (T0 / L) × [1 − (P / P0)^((R × L) / (g × M))]
Where T0 is sea level temperature in kelvin, L is lapse rate, P is observed pressure, P0 is sea level reference pressure, g is gravity, M is molar mass, and R is the universal gas constant.
ISA Temperature at Altitude ≈ 15 − 1.98 × (Altitude in ft / 1000)
This supporting value helps compare the entered ambient temperature against a standard atmosphere estimate.
How to Use This Calculator
- Choose the calculation mode you want highlighted in the results.
- Enter station pressure, altimeter setting, absolute pressure, and sea level pressure using any supported units.
- Provide field elevation and your reference temperatures.
- Leave the physical constants at standard values, or adjust them for specialized analysis.
- Set the maximum graph altitude to control the pressure curve display.
- Press the calculate button to show the result above the form.
- Use the CSV button to export the summary table.
- Use the PDF button to save the result section and chart.
Frequently Asked Questions
1) What is pressure altitude?
Pressure altitude is the height above the standard pressure datum. Pilots use it to compare current atmospheric pressure against standard conditions for performance calculations.
2) Why does altimeter setting change pressure altitude?
Altimeter setting adjusts local pressure to sea level conditions. When it differs from standard pressure, the correction changes the pressure altitude even if field elevation stays the same.
3) Why are there multiple altitude results?
The calculator compares three valid approaches: altimeter-based aviation pressure altitude, station-pressure altitude, and a more general barometric model altitude using adjustable atmospheric parameters.
4) Can I use hPa instead of inHg?
Yes. The calculator accepts hPa, kPa, Pa, inHg, mmHg, and psi. All pressure inputs are converted internally before altitude values are calculated.
5) Does temperature affect the pressure altitude formula?
Temperature does not directly change the basic altimeter pressure altitude shortcut. However, temperature affects atmospheric modeling and helps explain differences from ISA-based expectations.
6) Can this calculator handle locations below sea level?
Yes. Negative elevations or pressure combinations that imply below-sea-level altitude can still be processed, provided the physical inputs remain realistic and positive.
7) What does the Plotly graph show?
The graph plots modeled pressure against altitude using the current reference pressure, lapse rate, and temperature. It also highlights the main altitude result you selected.
8) Is this suitable for certified flight operations?
This tool is useful for education, planning, and quick analysis. Certified flight decisions should always rely on approved instruments, procedures, and official aviation data.