Does this work for Mars?

Yes, but with Martian values: P0 is approximately 636 Pa and H is approximately 11 100 m.

Why is the atmosphere assumed isothermal?

The exponential formula is exact for constant temperature. For real atmospheres with lapse rates, it is a good first approximation over limited altitude ranges.

At what altitude is pressure half of sea level?

Solving exp(-h/H) = 0.5 gives h = H * ln(2), approximately 5 900 m on Earth.

Free Atmospheric Pressure at Altitude Calculator

Calculate the atmospheric pressure at a given altitude using the barometric formula P = P0 * exp(-h / H), where H is the scale height.

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Surface Pressure (P0)

Altitude (h)

Scale Height (H)

Pressure at Altitude

56,266.42 Pa

Pressure (atm)0.555306 atm

Fraction of Sea-Level Pressure0.555306

Pressure at Altitude vs Surface Pressure (P0)

View formula & how it works →

Barometric Pressure at Altitude

For an isothermal atmosphere the pressure decreases exponentially with height.

Formula

P(h) = P0 * exp(-h / H)

*P0* = surface pressure

*h* = altitude above the surface

*H* = scale height (about 8.5 km for Earth)

Every scale height of ascent reduces the pressure by a factor of e (about 2.718).

Example Calculation

Earth at 5 000 m altitude (P0 = 101 325 Pa, H = 8 500 m).

01P = P0 * exp(-h/H)
02P = 101325 * exp(-5000/8500)
03exp(-0.5882) = 0.5556
04P = 101325 * 0.5556 = 56 300 Pa = 0.556 atm

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