Pressure from Altitude Calculator

Compute air pressure at a given altitude from sea level pressure and temperature using the standard atmosphere formula, plus pressure ratio and boiling point drop.

Input

Enter an altitude and the sea level pressure and temperature to compute the air pressure at that height using the standard atmosphere formula.

Altitude

Height above sea level of the point (for example 3776 m for Mount Fuji)

Sea level pressure

hPa

Reference pressure at sea level. The standard value is 1013.25 hPa.

Sea level temperature

deg C

Temperature at sea level. The standard value is 15 degrees.

Result

Pressure at this altitude

634.659519hPa

Value at an altitude of 3,776 m.

Ratio to sea level

62.636025 percent

Estimated boiling point

88.864986 deg C

Estimated local temperature

-9.544 deg C

Approximated with the standard atmosphere formula P=P0(1-0.0065h/T0)^5.255. The boiling point drop is a reference value.

How it works

Pressure is computed with P=P0(1-L*h/T0)^5.255, where L is the lapse rate 0.0065 K/m, T0 is sea level temperature in kelvin, and the exponent 5.255 comes from the standard atmosphere.
The standard sea level pressure P0 is 1013.25 hPa and the standard sea level temperature is 15 degrees Celsius (288.15 K).
The local temperature estimate subtracts the lapse rate 0.0065 K/m times the altitude from the sea level temperature.
The boiling point estimate uses an approximation of about 1 degree Celsius drop per about 34 hPa of pressure decrease and is a reference value.
This is an approximation based on the troposphere model of the International Standard Atmosphere; real pressure varies with weather and latitude.

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