Plumbing Pipe Sizing Calculator Plumbing Pipe Sizing Calculator Desired Flow Rate (Q) GPM (US) LPM m³/s Maximum Fluid Velocity (V) ft/s m/s Guideline: Keep below 5-8 ft/s (1.5-2.4 m/s) for copper/plastic supply lines to reduce noise and erosion. Drainage pipes typically require lower velocities for solids transport. Calculate Required Pipe Size Required internal pipe diameter will appear here... Download Calculation as PDF
