Estimate the flow rate of a pipe from pressure and diameter.
Pressure first becomes an equivalent water head in feet, which drives the flow velocity. That velocity times the pipe cross-section area yields gallons per minute. Estimating flow helps size drain systems, plan irrigation and judge whether a fixture will keep up with demand.
Plumbing Flow Rate
Velocity = sqrt(2 x g x head); flow = velocity x pipe area
Velocity = sqrt(2 x g x head); flow = velocity x pipe area Pressure first becomes an equivalent water head in feet, which drives the flow velocity. That velocity times the pipe cross-section area yields gallons per minute.
Estimating flow helps size drain systems, plan irrigation and judge whether a fixture will keep up with demand.
This calculator takes 2 inputs: Water pressure, Pipe inner diameter. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.