Friction Loss Calculator

What Is Friction Loss in Pipes?

Friction loss is the energy a fluid loses as it flows through a pipe because of viscous drag against the wall. Engineers express it as head loss (height of fluid column) or pressure drop. The Darcy-Weisbach equation is the standard method for both laminar and turbulent pipe flow. For related calculations, see the Darcy-Weisbach Equation Calculator and Reynolds Number Calculator.

Darcy-Weisbach Head Loss Formula

Head loss is given by h_f = f × (L/D) × (V²/2g), where f is the Darcy friction factor, L is pipe length, D is diameter, V is average velocity, and g is gravitational acceleration. Pressure drop follows ΔP = ρ × g × h_f, where ρ is fluid density.

Key Factors

• Friction factor (f): Depends on Reynolds number and pipe roughness. Use f = 64/Re for laminar flow.
• Pipe geometry: Longer pipes and smaller diameters increase head loss.
• Velocity: Head loss scales with V², so doubling velocity quadruples the loss.
• Fluid density: Denser fluids produce higher pressure drops for the same head loss.