How it's calculated
Q = V ÷ t or Q = π(d/2)² × v
V = volume, t = time, d = pipe inner diameter, v = flow velocity, A = π(d/2)² = cross-section area. Q = volumetric flow rate, reported as L/min, m³/h, GPM and CFM.
Common questions
How do I get flow rate from pipe size?
Multiply the pipe's cross-sectional area by the fluid velocity. The calculator does this once you enter diameter and velocity.
What is GPM?
Gallons per minute, the common US unit for pumps and plumbing flow. The tool can also report L/min, CFM, and m³/s.