How this gas cylinder run time calculator works
A gauge reading on its own does not say how many minutes of gas are left. This page converts the content of the cylinder to its volume at atmospheric pressure from the water volume and the gauge pressure, then divides what is left above your stop pressure by the flow rate to give a run time in hours and minutes.
The formula applied is Boyle law, free gas = water volume x (gauge pressure + atmospheric pressure) / atmospheric pressure, and the run time is the converted volume between the current and stop pressures divided by the flow rate. The standard atmosphere of 14.696 psi (1.01325 bar) is used. The stop pressure was not confirmed from an authoritative source, so no figure is supplied and your own value is applied as entered. Figures reflect October 2026 and the underlying values come from secondary sources, so checking the originals is advised.
No temperature correction or compressibility factor is applied, so the real contents can differ, and the run time is rounded down to stay on the safe side. Air consumption of pneumatic equipment and the sizing of compressors or receiver tanks are not covered. Pressures go in psi gauge, the water volume in cubic feet or liters and the flow rate in SCFH or liters per minute; volumes are shown in cubic feet with liters in parentheses. This calculator is for reference and does not replace design. Review by a qualified engineer is required.
Frequently asked questions
It is on the label or the supplier data sheet, in liters or cubic feet. If the shoulder shows only a water capacity in pounds, divide it by about 62.4 to get cubic feet. It is the internal volume of the shell, not the charged gas quantity.
Yes. This page applies Boyle law only and does not correct for temperature. A cold cylinder reads a lower pressure and so looks emptier, and a warmed one looks fuller.
Use the value set by your equipment or work instruction. No authoritative stop pressure was confirmed, so none is supplied here. Entering 0 assumes the cylinder is drawn down to atmospheric pressure.