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Atmospheric Pressure At Altitude Calculator

Work out atmospheric pressure at altitude instantly with clear inputs, formula shown and shareable results.

About Atmospheric Pressure At Altitude Calculator

The barometric formula for the standard troposphere gives pressure as sea level pressure times (1 - 0.0065h/288.15)^5.25588. At 2500 m that is 747 hPa, 74% of sea level, and water boils near 92 C. Pressure halves roughly every 5500 m, which is why supplemental oxygen becomes necessary above about 3500 m.

Formulas

Barometric formula

P = P0 (1 - 0.0065 h / 288.15)^5.25588

Boiling point

falls about 1 C per 300 m of altitude

Worked example

With the default values below, Atmospheric Pressure At Altitude Calculator returns Atmospheric Pressure of 746.83. Change any input above and every figure here is recalculated in your browser.

Inputs used

Altitudeminimum 0 m
2,500 m
Sea level pressureminimum 1 hPa
1,013.25 hPa

Results

Atmospheric Pressure
746.83 hPa
Fraction Of Sea Level Pressure
0.7371
Same Pressure In Kilopascals
74.683
Approximate Boiling Point Of Water
91.8 C

Step by step

  1. 1Values used
  2. 2Barometric formula
  3. 3Boiling point
  4. 4Atmospheric Pressure= 746.83 hPa
  5. 5Fraction Of Sea Level Pressure= 0.7371
  6. 6Same Pressure In Kilopascals= 74.683
  7. 7Approximate Boiling Point Of Water= 91.8 C

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is the exponent 5.25588?

It is gM/(R x lapse rate) for the standard atmosphere, which is what integrating the hydrostatic equation with a linear temperature profile produces.

Why does cooking take longer at altitude?

Because the lower boiling point limits temperature. At 2500 m water boils at 92 C, so simmering is 8 degrees cooler.

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