Pressure at Altitude Calculator
Pressure at altitude calculator works out Pressure altitude and Density altitude from Field elevation or altitude, Altitude unit and Altimeter setting (QNH). The default figures on this page give static pressure of 1,013.250 hPa; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
3 steps
- ISA at 0 ft: T = 288.15 - 0.0065 x 0 = 288.15 K.
- p = 101325 x (1 - 0.0065 x 0 / 288.15)^5.255786 = 101325 Pa = 1013.25 hPa.
- rho = p / (R T) = 101325 / (287.058 x 288.15) = 1.224978 kg/m3.
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
4 sources
What the pressure at altitude calculator calculates
Works the ICAO Standard Atmosphere and the basic aerodynamic relations: pressure altitude, density altitude, pressure, temperature and density at altitude, true airspeed, Mach number, dynamic pressure, lift and drag, wing loading and stall speed.
How to use this pressure at altitude calculator
Enter Field elevation or altitude, Altitude unit, Altimeter setting (QNH) and Pressure unit. Pressure altitude updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Pressure altitude, Density altitude and Static pressure.
The method follows ICAO Doc 7488, Manual of the ICAO Standard Atmosphere (extended to 80 km), U.S. Standard Atmosphere, 1976 (NASA-TM-X-74335), NASA Glenn Research Center, Beginner’s Guide to Aeronautics: lift and drag equations, dynamic pressure, speed of sound and FAA Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 4.
What you can compare
Change one input at a time to see how it affects Pressure altitude, Density altitude and Static pressure. The inputs you can vary are Field elevation or altitude, Altitude unit, Altimeter setting (QNH), Pressure unit, Outside air temperature and Temperature unit.
Understanding Pressure altitude, Density altitude and Static pressure
For planning and study. Aircraft performance must be taken from the approved flight manual for the specific aircraft; the standard atmosphere describes a reference day, not the one you are flying in.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How to calculate pressure at altitude?
Works the ICAO Standard Atmosphere and the basic aerodynamic relations: pressure altitude, density altitude, pressure, temperature and density at altitude, true airspeed, Mach number, dynamic pressure, lift and drag. Open “How this is worked out” beside the result to see each step for your own figures.
How much does pressure drop per 1000 feet altitude?
On the figures this page opens with — field elevation or altitude 5,000 — the static pressure is 1,013.25 hPa. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
What information do I need for the pressure at altitude calculator?
You need Field elevation or altitude, Altitude unit, Altimeter setting (QNH), Pressure unit, Outside air temperature, Temperature unit, Airspeed (calibrated, or true for Mach) and Speed unit. The page opens with default figures that give static pressure of 1,013.250 hPa, so you can see the scale before entering your own.
What does this pressure at altitude calculator show?
It shows Pressure altitude, Density altitude, Static pressure, Temperature used, Air density, Density ratio to sea level, Speed of sound and True airspeed, with the working and any warnings for your entries.
Can I check how the pressure at altitude calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.