Oxygen Therapy Calculator

O2 flow rate to FiO2 conversion and cylinder duration estimation.

O2 Flow Rate (L/min)

Delivery Device

Cylinder Pressure (psi)

Cylinder Size

Target SpO2 (%)

Tab to move between fields

Estimated FiO2 (%)

29%

Cylinder Duration (min)280

Cylinder Duration (hrs)4.7

Estimated PAO2 (mmHg)156.8

Flow Rate (L/min)2

Approx Min Flow2

How to Use This Calculator

Enter the O2 flow rate (L/min) and select the delivery device (nasal cannula, simple mask, or NRB).
Select cylinder size and enter current cylinder pressure (psi).
Set target SpO2 (%) to confirm the prescribed flow rate should achieve your oxygenation goal.
Review estimated FiO2, cylinder duration in minutes and hours.
Plan oxygen refills based on duration -- keep a backup cylinder when duration is less than 8 hours.

How the result changes with O2 Flow Rate (L/min)

O2 Flow Rate (L/min): Oxygen flow rate in liters per minute.
Delivery Device: Select oxygen delivery device.
Cylinder Pressure (psi): Remaining pressure in the oxygen cylinder (psi).
Cylinder Size: Select oxygen cylinder size.
Target SpO2 (%): Desired oxygen saturation target (typically 88-92% for COPD, 94-98% otherwise).

Estimated FiO2 (%): Approximate fraction of inspired oxygen delivered by the device at this flow rate.
Cylinder Duration (min): Estimated time until cylinder empties at current flow rate.
Cylinder Duration (hrs): Cylinder duration in hours.
Estimated PAO2 (mmHg): Estimated alveolar oxygen partial pressure from the alveolar gas equation (sea level, PaCO2=40).
Flow Rate (L/min): Current oxygen flow rate.

Identify Input Parameters
4 parameters
O2 Flow Rate (L/min) = 2, Delivery Device = 0, Cylinder Pressure (psi) = 2000, Cylinder Size = 0 = 5 input(s) provided
Calculate Estimated FiO2
29 = 29
Calculate Cylinder Duration
280 = 280
Calculate Cylinder Duration
Cylinder Duration = durationMin / 60
4.7 = 4.7