Free tool
Pressure altitude calculator
Pressure altitude is the height in the standard atmosphere where today’s pressure would be found. Enter the field elevation and altimeter setting; add the temperature for density altitude.
Pressure altitude formula
The rule pilots learn: PA = elevation + (29.92 − altimeter) × 1000. It is close at low airports and drifts a little higher up. The calculator converts the altimeter setting to station pressure and solves the standard-atmosphere equation exactly:
PA (ft) = 145,366.45 × [1 − (P_station / 1013.25)^0.190284]
Density altitude
Density altitude adds temperature. The standard (ISA) temperature is 15 °C at sea level and falls about 2 °C per 1,000 ft. Every degree warmer than ISA adds about 119 ft: DA ≈ PA + 118.8 × (OAT − ISA). On a 35 °C afternoon at a 5,000 ft airport the air behaves as if it were about 8,500 ft.
Altitude from a barometer
The same physics lets a barometer act as an altimeter: h = 44,330.8 × [1 − (P / P₀)^0.190263] meters. The catch is P₀ — the sea-level pressure changes with the weather, by enough to shift the answer by several hundred feet. That is why altimeters are reset to the local setting. Pressure altitude explained
Frequently asked questions
What is the pressure altitude formula?
The quick rule is: pressure altitude = field elevation + (29.92 − altimeter setting in inHg) × 1,000 ft. The exact form uses the standard atmosphere: PA = 145,366.45 × [1 − (station pressure ÷ 1013.25 hPa)^0.190284] ft. This calculator uses the exact form.
How do I calculate pressure altitude?
Enter the field elevation and the current altimeter setting (from the METAR or ATIS). Or set your altimeter to 29.92 inHg (1013 hPa) and read the altitude it shows: that is the pressure altitude.
What is the difference between pressure altitude and density altitude?
Pressure altitude corrects only for non-standard pressure. Density altitude also corrects for temperature: hot air is thinner, so on a hot day an aircraft or engine performs as if it were much higher. Density altitude ≈ pressure altitude + 118.8 × (outside air temperature − ISA temperature).
How do I find altitude from barometric pressure?
Use the barometric formula: altitude = 44,330.8 × [1 − (P ÷ P₀)^0.190263] meters, where P is the measured pressure and P₀ the sea-level pressure (1013.25 hPa if unknown, better the local value from a weather report).