Work out oxygen requirement at altitude instantly with clear inputs, formula shown and shareable results.
Supplemental oxygen quantity is flow rate per person multiplied by occupants and duration. The required inspired oxygen fraction is the fraction that restores sea-level partial pressure of oxygen at the cabin altitude, which is why around 34,000 ft demands essentially 100% oxygen and above that a pressure-demand system.
Oxygen quantity
Total = flow per person x occupants x minutes; required O2 fraction = 0.2095 x P(sea level) / P(altitude)
Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.
Rules vary, but a common structure is crew oxygen above 10,000-12,500 ft cabin altitude for extended periods and passenger oxygen available above 15,000 ft. Check the applicable regulation.
Even breathing pure oxygen the ambient pressure is too low to load the blood adequately, so pressure-demand equipment or a pressurised cabin is required.