Air Pressure at Altitude Calculator
Enter an altitude in metres to get the atmospheric pressure in pascals using the barometric formula — and see how steeply the air thins as you climb.
Pressure at any height
Enter an altitude in metres and the calculator returns the standard atmospheric pressure at that height in pascals (Pa).
Troposphere only
The barometric formula here is valid up to 11 km — the top of the troposphere — and assumes the International Standard Atmosphere.
What is air pressure at altitude?
How the atmosphere thins as you climb
The air pressure altitude calculator turns a height above sea level into the atmospheric pressure you would feel there. Air pressure is the weight of the column of air pressing down from above, so the higher you go the less air remains overhead and the lower the pressure falls. At sea level the standard pressure is 101 325 Pa (about 1013 hPa); on a 2000 m mountain it has already dropped to roughly 79 500 Pa. This calculator uses the barometric formula for the troposphere to convert any altitude up to 11 km into pressure, which matters for weather, aviation, boiling points, and how your body copes at height.
Enter an altitude in metres up to 11 000 m to get the standard atmospheric pressure at that height in pascals instantly.
The pressure is the sea-level pressure multiplied by a factor that shrinks with height, raised to a fixed exponent.
P = P₀ × (1 − 2.25577e-5 × h)^5.25588Here P₀ is the sea-level pressure of 101 325 Pa and h is the altitude in metres. The term inside the brackets falls steadily as you rise, and the exponent 5.25588 comes from the standard temperature lapse rate of the troposphere. Because the bracket is raised to that power, pressure drops fastest near the ground and more gently higher up.
Suppose you are standing on a 2000 m peak and want the air pressure there.
Scale the altitude
2.25577e-5 × 2000 = 0.04512 — the fraction the bracket loses at this height.
Form the base
1 − 0.04512 = 0.95488 — the base of the power term.
Raise and scale
101325 × 0.95488^5.25588 ≈ 79,495 Pa (about 79.5 kPa) — the air pressure at 2000 m.
The number tells you how thin the air is at that height. At sea level you get the full 101 325 Pa, but pressure falls quickly with altitude: by 1000 m it is about 89 875 Pa, roughly 12% lower than at sea level, and by 5000 m it has nearly halved to about 54 000 Pa. This decline is why water boils at a lower temperature up a mountain, why aircraft cabins are pressurised, and why climbers feel breathless at altitude — each breath delivers less oxygen because there are fewer air molecules in the same volume. The drop is steepest in the first few kilometres, so even a modest hill noticeably lowers the pressure, while gaining height in the thin upper troposphere changes it more slowly.
The formula is a clean model, but a couple of practical points are worth keeping in mind.
Standard atmosphere, troposphere only
This calculator uses the International Standard Atmosphere, so it gives the pressure for a fixed sea-level value and a standard temperature profile — real weather raises or lowers the pressure by a few percent from day to day. The barometric formula here is valid only within the troposphere, up to about 11 km, and it ignores humidity and local weather systems. For altitudes above 11 km the model no longer applies and the calculator returns no result.