Oxygen Tank Duration Calculator
Estimate how long a gas cylinder lasts.
A cylinder's duration depends on its gas volume, pressure and your breathing rate.
The math behind it
duration = tank volume x pressure / (consumption x ATA). Underwater, ATA = 1 + depth/10 increases consumption.
Worked example
A 12 L tank at 200 bar with 20 L/min at the surface lasts about 120 minutes.
FAQ
Why does depth shorten it?
Pressure compresses the gas, so each breath uses more of it.