Hydraulic calculator

Pipe Flow & Friction Loss

Enter flow in US GPM, choose the pipe material and nominal size, and calculate water velocity plus straight-pipe friction head for 100 ft of pipe.

Water temperature: 60°F

Inputs

Flow rate

US GPM

Water temperature

°F

Used for water viscosity and density in Darcy–Weisbach calculations.

Friction calculation method

Pipe material

Nominal pipe size

Enter a flow rate greater than 0 GPM.

Calculations update automatically. Nominal size is converted to the actual inside diameter for the selected pipe.

Results

Turbulent flow

Water velocity

—ft/s

Average velocity through the pipe I.D.

Friction loss / 100 ft

—ft TDH

Straight-pipe Darcy–Weisbach head loss

Inside diameter

—

Pressure drop

—

Reynolds no.

—

Darcy factor

—

Calculation basis

Darcy–Weisbach: 100 ft of straight pipe. Water viscosity and density are calculated from the selected temperature. Turbulent friction factor is solved with the Colebrook equation using a smooth-pipe roughness of 0.000005 ft; laminar flow uses 64/Re.

Hazen–Williams mode uses the U.S. customary head-loss form h_f = 0.002083L(100/C)^1.85Q^1.85/d^4.8655, with head loss in feet, Q in US GPM, d in inches, and L in feet. Default C values are 150 for PVC and 140 for copper and can be edited.

TDH shown here is pipe friction only. It does not include fittings, valves, strainers, heaters, filters, equipment losses, elevation/static head, entrances, exits, or other minor losses.