Use this calculator for flight-planning study or a first-pass cross-check when all inputs describe the same aircraft, atmospheric condition, and phase of flight.

Usable oxygen (L)

Total usable oxygen volume at cylinder pressure.

Flow rate (L/min)

Consumption rate of all users combined.

Compute how long the onboard oxygen lasts at a given crew or passenger flow rate. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Duration (h)

Oxygen endurance.

• Do not use a generic calculator in place of the current aircraft flight manual, approved performance data, operating limitations, NOTAMs, weather, or regulations. Real performance changes with configuration, runway condition, altitude, temperature, wind, loading, and technique.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Cross-check the result against the aircraft flight manual or approved planning system, then apply the required safety margins. Keep signed wind, heading, altitude, speed, and fuel conventions explicit.

• Oxygen Required Calculator

  Compute the onboard oxygen volume required for a duration at a given combined flow rate.

• Endurance Calculator

  Compute how long the usable fuel lasts at a given consumption rate.

• Oxygen Altitude Threshold

  Compare a flight altitude with a threshold supplied by the user and calculate feet above or below that threshold. Oxygen rules vary by jurisdiction, aircraft, duration, and crew/passenger status; this tool does not choose a legal threshold.