Reverse Flow Calculator

Work backwards from the pressure you're pumping: estimate what the line is actually flowing — and what the nozzle is really getting.

Calculation mode

You assert the nozzle pressure (the classic method): whatever PDP is left becomes friction loss, and flow falls out.

Pump discharge pressure (psi)

Nozzle pressure (psi)

The pressure you're asserting the nozzle gets (smooth bore handline 50, fog 100).

Hose diameter (in)

Hose length (ft)

Appliance loss (psi)

Elevation gain/loss (ft)

Enter values above to see the result.

Prove it on the panel: set a PDP with the throttle and compare the line's live flow readout with this estimate. Open the pump panel