Output Pressure

Set at the regulator rather than the tank, output pressure is what actually reaches the solenoid on each shot, measured in bar or psi and typically adjustable within a safe range printed by the regulator's manufacturer.

Because pressure and FPS scale together fairly predictably on a well-sealed system, most HPA players chrono once, note the pressure that hit their field's limit, and dial the regulator back to that number rather than guessing — one of the reasons HPA is popular for fields that enforce tight power tolerances.

Two identical guns with slightly different output pressure settings can chrono a few FPS apart even with the same BB and barrel, which is why a shared loadout or squad build usually standardises this number across every gun in use.