Water Flow Rate Calculator (GPM)

How much water flow can a pipe carry?

Find available flow mode solves the Hazen-Williams equation in reverse, computing the maximum GPM a known diameter and material can carry within the available pressure drop you enter over the run length. It reports the resulting velocity and friction loss so you can confirm the pipe stays within its velocity ceiling. Fittings are included as equivalent straight-pipe length per Crane TP-410.

Related questions

• What size water pipe do I need for a given GPM?
• Why does the hot water line option lower the velocity limit?