Free Pipe Flow and Head Loss Calculator

Select pipe material, nominal diameter, and flow in US GPM to estimate water velocity in feet per second and friction head in feet per 100 feet of straight pipe.

Pipe types and inside diameter

Choose Copper Type L, Steel Schedule 40 or representative PEX tubing. Velocity uses the selected pipe's inside diameter, not its nominal size. Verify actual product dimensions, especially PEX.

Water at 60°F; new, clean pipe

The tool uses Darcy-Weisbach head loss and Colebrook turbulent friction. Laminar flow uses 64/Re; transitional flow is labelled as an approximate blend. These assumptions are estimates, not a substitute for project-specific design.

Results exclude fittings, valves, equipment resistance, elevation and glycol. They are not total pump head or a pump selection.