Darcy-Weisbach Pressure Loss

Calculate straight-pipe major pressure loss and head loss from a user-supplied Darcy friction factor.

Concept

Results

Enter inputs and select Calculate to display reviewed results.

Inputs

Pipe length *

Pipe inside diameter *

Average velocity *

Density *

Darcy friction factor *

Enter the Darcy friction factor, not the Fanning friction factor.

Formula & Variables

Δp = fLDρV²2h_f =Δpρg

Δp: Pressure loss; [Pa]
f: Darcy friction factor; [1]
L: Length; [m]
D: Inside diameter; [m]
ρ: Density; [kg/m^3]
V: Velocity; [m/s]

Assumptions

Straight, constant-diameter circular pipe.
Steady incompressible flow with constant density.
The entered friction factor is Darcy friction factor.
Major friction loss only.

⚠ Limitations

Does not solve Colebrook, Moody chart, or turbulent friction factor.
Minor losses, elevation head, pump work, and compressible gas pressure drop require separate calculation methods.