How long does it take to fill air tanks?

How long does it take to fill a 30.5 in^3 air tank at 120 psi using the
1.03cfm air compressor?

What’s confusing is the cfm is only given at 0psi.

According to my math .13 gal (30.5 in^3) * 83 sec (1min 26sec as per site)/.5 gal = 21.58 sec to fill to 120 psi.

In competition you will almost never have to fill the tanks from empty though. You should pre-charge them before a match to be sure you have air pressure at start up and also so you won’t be running the compressor non-stop. We generally tether up and run ours while in que to be sure that we are topped off.

Even so, the best way to know is to hook up your compressor and run it until you hit 120 psi. Every compressor is a little bit different, some are new, some are old, some are well cared for, others abused. The best way to know how long it takes for your compressor to fill a tank is to fill a tank with your compressor.