Case 1
- Height above sea level
- 0m
101,325.00Pa
Open with these valuesAir Pressure at Altitude Calculator
89,874.56Pa
Result: 89,874.56 PaPressure falls by roughly 12 % over the first kilometre and is down to a third of sea level on the summit of Everest. Enter the height in metres and read the pressure of the standard atmosphere in pascals. The formula holds to 11000 m, where the troposphere ends.
Worked examples
Case 2
- Height above sea level
- 1000m
89,874.56Pa
Open with these valuesCase 3
- Height above sea level
- 8848m
31,443.96Pa
Open with these valuesHow it's calculated
p = 101325 × (1 - 2.25577e-5 × h)^5.25588
- StepEnter the height above sea level in metres.
- StepRead the pressure of the standard atmosphere in pascals.
- ResultDivide by 1000 for kilopascals, or by 100 for the millibars on a barometer.
Reference table
| Height | Place | Pressure |
|---|---|---|
| 0 | Sea level | 101325.00 |
| 1000 | Alpine valley | 89874.56 |
| 2000 | Mountain hut | 79495.20 |
| 5000 | Everest base camp | 54019.88 |
| 8848 | Summit of Everest | 31443.96 |
| 11000 | Cruising altitude | 22632.03 |
Questions
How much does air pressure drop per 100 metres?
About 1200 pascals, or 12 millibars, near sea level. The drop gets smaller with height because the air is already thinner, so it is not a straight line.
Why does the calculator stop at 11000 metres?
Because this formula describes the troposphere, where temperature falls steadily by 6.5 kelvin per kilometre. Above the tropopause the temperature stops falling and a different equation takes over.
Is this the pressure my barometer will show?
Not exactly. This is the standard atmosphere, an agreed average; real weather shifts sea level pressure by several thousand pascals in either direction.
What is the pressure on top of Everest?
About 31400 pascals in the standard atmosphere, roughly 31 % of the sea level value. That is why climbers above 8000 metres normally carry oxygen.
Sources and last check
Information, not professional advice.