Altitude Pressure Calculator
Air pressure, temperature, boiling point and oxygen partial pressure at altitude.
Results
What this tool does
Uses the International Standard Atmosphere, which assumes sea level at 15 °C and 1013.25 hPa with temperature falling 6.5 °C per kilometre. Real weather departs from it daily, so treat the result as the reference case rather than today's reading. Above 11 km the model changes and this one no longer applies.
Formula
p = p₀ (1 − 0.0065 h ÷ 288.15)^5.255 88 (standard atmosphere)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
h | Altitude | m |
p0 | Sea level pressure | hPa |
t0 | Sea level temperature | °C |
P | Pressure | hPa |
PC | Percentage | % |
T | Temperature | °C |
BP | Boiling point | °C |
O2 | Oxygen partial pressure | hPa |
Worked example
- Altitude2000 m
- Sea level pressure1013.25 hPa
- Sea level temperature15 °C
- Pressure794.952 hPa
- Percentage78.456 %
- Temperature2.000 °C
- Boiling point93.217 °C
- Oxygen partial pressure166.542 hPa
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.
Frequently asked questions
Why does food take longer to cook up a mountain?
Because water boils at a lower temperature when there is less air pressing on it, and boiling water is as hot as the pot will ever get. At 2000 metres it boils near 93 °C, and food cooked in it is being cooked seven degrees cooler, which stretches the time considerably. A pressure cooker exists to undo exactly this.