Oxygen Tank Duration Calculator
Find out how many minutes your oxygen cylinder will last by entering the current pressure gauge reading, cylinder size, and prescribed flow rate. A 200 PSI safety reserve is subtracted by default — adjust the residual field if your equipment specifies a different threshold.
Cylinder size
PSI
L/min
PSI
Time at the selected flow rate before reaching residual pressure
- 1
Usable pressure
2,000 − 200 = 1,800 PSI - 2
Usable O₂ volume
1,800 × 0.28 = 504 LCylinder factor converts gauge pressure to litres of available gas. - 3
Duration
504 ÷ 2 = 252
How does this calculator work?
Duration (min) = (current PSI − 200) × cylinder factor ÷ flow rate. An E cylinder (factor 0.28) at 2,000 PSI and 2 L/min lasts (1,800 × 0.28) ÷ 2 = 252 minutes (≈ 4.2 h). Select your cylinder type, enter the gauge reading and flow rate for an instant estimate.
Formula
How this is calculated
Each medical oxygen cylinder type has a published "cylinder factor" — litres of gas available per PSI of gauge pressure, derived from the cylinder's internal volume and rated service pressure. Subtracting the safe residual pressure (commonly 200 PSI) from the current gauge reading gives the usable pressure. Multiplying by the cylinder factor converts that pressure into litres of oxygen, and dividing by the flow rate in L/min gives the duration in minutes.
Cylinder factors used here are the clinically accepted standard values for US medical cylinders: D = 0.16, Jumbo D = 0.23, E = 0.28, M = 1.56, G = 2.41, H/K = 3.14 L/PSI. These assume dry oxygen at room temperature at the standard 2,200 PSI service pressure. Small variations occur with ambient temperature and cylinder age.
This calculator provides a planning estimate. Always arrange a spare cylinder or portable concentrator for continuous oxygen therapy and never allow the tank to reach zero pressure — the regulator loses accuracy at very low pressures, delivering less oxygen than prescribed.
Frequently asked questions
The cylinder factor (L/PSI) converts the cylinder's gauge pressure into the volume of gas available. It equals the cylinder's internal volume divided by its service pressure. Common values: E = 0.28, D = 0.16, H/K = 3.14 L/PSI.
Below about 200 PSI the regulator cannot maintain an accurate, consistent flow rate, so the patient may receive less oxygen than prescribed. The reserve is a safety margin and a prompt to switch cylinders before the tank is empty.
Cylinder duration depends only on the gauge pressure, cylinder factor, and flow rate — not on altitude. However, some patients require a higher flow rate at altitude, which would shorten the usable time. Check with your clinician if travelling to high elevation.
Also known as
TG we-Calculate Editorial Team. (2026). Oxygen Tank Duration Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/oxygen-tank-duration-calculator
TG we-Calculate Editorial Team. "Oxygen Tank Duration Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/oxygen-tank-duration-calculator.
TG we-Calculate Editorial Team, "Oxygen Tank Duration Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/oxygen-tank-duration-calculator
@misc{wecalculate_oxygen_tank_duration_calculator, title = {Oxygen Tank Duration Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/oxygen-tank-duration-calculator}}, year = {2026}, note = {TG we-Calculate} }
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