Gas Partial Pressure Calculator

Gas Partial Pressure Calculator (Dalton's Law)

In any gas mixture, each component contributes to the total pressure exactly as if it alone filled the container - this is Dalton's Law, one of the foundational relationships in gas mixture behavior.

Formula: P_i = x_i × P_total

Example: oxygen at 20.9% mole fraction in air at standard atmospheric pressure (101.325 kPa) has a partial pressure of 21.18 kPa - the actual physiological driving pressure your lungs work with, not the full atmospheric pressure.

How to Use This Calculator

1. Enter the mole fraction of the gas component (0 to 1).
2. Enter the total mixture pressure.

This is exactly why oxygen partial pressure, not total atmospheric pressure, is what determines breathing physiology at altitude - even though total pressure and oxygen fraction both matter, it is their product that counts.