Barometric Pressure at Altitude Calculator

How Does Pressure Change with Altitude?

Atmospheric pressure decreases as you climb because there is less air above you. The barometric formula models this drop using the International Standard Atmosphere (ISA) lapse rate of 6.5 K/km below 11 km.

Barometric Formula

$$P = P_0 \left(1 - \frac{L\,h}{T_0}\right)^{\frac{gM}{RL}}$$

where $P_0$ is sea-level pressure, $h$ is altitude (m), $L = 0.0065$ K/m is the lapse rate, $T_0 = 288.15$ K is sea-level temperature, $g = 9.80665$ m/s², $M = 0.0289644$ kg/mol, and $R = 8.314$ J/(mol·K). The exponent $gM/(RL) \approx 5.256$.

Example: at 1000 m with $P_0 = 1013.25$ hPa, pressure is about 898 hPa — roughly 89% of sea level.

Frequently Asked Questions

What altitude does this formula cover?

The ISA barometric formula is valid in the troposphere, roughly 0–11 km. Above that, the lapse rate changes and a different model is needed.

Can I change sea-level pressure?

Yes. Standard sea-level pressure is 1013.25 hPa, but weather systems shift it. Enter the current local pressure for better estimates.

Why do ears pop when climbing?

External air pressure drops faster than pressure in your middle ear. The pressure difference pushes on your eardrum until it equalizes.

How does this relate to weather?

Barometric pressure at a fixed altitude tracks weather. This calculator estimates pressure at a new altitude assuming ISA temperature profile.

What is pressure at the summit of Everest?

At about 8849 m, pressure is roughly 33% of sea level (~337 hPa), which is why supplemental oxygen is often required.

Report

Air Pressure at Altitude Calculator

How Does Pressure Change with Altitude?

Barometric Formula

Frequently Asked Questions

Related Tools

Recent Visits