Air pressure at altitude calculator
Atmospheric pressure, temperature and air density at a given altitude.
Fill in the fields and the result will appear here automatically.
Obtain model pressure, temperature and density in the first standard-atmosphere layer for heights −430 to 11000 m. This is a consistent calculation with stated constants, not a weather forecast or measured route pressure.
How it works
Formula and logic
T=288.15−0.0065 h K; p=101325·(1−0.0065 h/288.15)^(9.80665·0.0289644/(8.314462618·0.0065)) Pa. Density ρ=p·0.0289644/(8.314462618·T). This power law uses a linear temperature lapse, not an isothermal exponential.
Example
At 2000 m the model gives 79.496 kPa,596.27 mmHg,2 °C and about 1.006 kg/m³. h=0 returns 101.325 kPa before rounding and 15 °C.
Fields and units
- Altitude above sea level — m
How to use
- — Enter metres relative to the adopted sea-level datum.
- — Use a barometer for actual pressure; this form has no weather correction.
- — kPa and mmHg rows express the same model pressure in different units.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- NASA/NOAA 1976: standard layer and geopotential height; constants differ
- Limitation
- Height is the adopted standard-model coordinate; geometric height is not separately converted to geopotential height. The 11000 m boundary belongs to the model layer, not a fixed tropopause in all weather. Humidity, season and actual pressure changes are excluded. The adopted rounded R=8.314462618 means this does not literally reproduce every constant in the 1976 tables.
FAQ
Why does pressure not fall in proportion to height?
T=288.15−0.0065 h K; p=101325·(1−0.0065 h/288.15)^(9.80665·0.0289644/(8.314462618·0.0065)) Pa. Density ρ=p·0.0289644/(8.314462618·T). This power law uses a linear temperature lapse, not an isothermal exponential.
Does the oxygen fraction change with altitude?
No, it stays near twenty-one per cent up to very great heights. What changes is the number of molecules in the same volume — which is exactly why oxygen runs short while its percentage does not.
Why is the upper bound eleven kilometres?
Height is the adopted standard-model coordinate; geometric height is not separately converted to geopotential height. The 11000 m boundary belongs to the model layer, not a fixed tropopause in all weather. Humidity, season and actual pressure changes are excluded.
How does this compare with a barometer?
A barometer measures actual pressure. Departure from the standard model is not pressure tendency: tendency means change over time. This form has neither time nor weather observations.