How to find friction factor f?

Laminar: f=64/Re | Turbulent: Colebrook or Moody chart

Darcy-Weisbach Pressure Drop

Calculate frictional pressure loss in pipes using Darcy-Weisbach equation. Automatic friction factor from Moody chart (Colebrook). Laminar & turbulent flow.

Pressure Drop ΔP

45 kPa

100mm pipe, 2 m/s water, L=100m

Pipe Pressure Drop

Featured: Darcy Friction f • Head Loss • Moody Chart

Pipe Diameter D (mm)

Pipe Length L (m)

Volume Flow Rate Q (m³/h)

Roughness ε (mm) Steel: 0.046, PVC: 0.0015

Density ρ (kg/m³)

Dynamic Viscosity μ (cP)

Moody Diagram Position

Friction factor f vs Reynolds number

Darcy-Weisbach Equation

ΔP = f (L/D) (ρ v² / 2)
h_f = f (L/D) (v² / 2g)

Friction Factor

Laminar: f = 64 / Re
Turbulent: Colebrook → 1/√f = -2 log(ε/(3.7D) + 2.51/(Re √f))

Enter pipe parameters to see results

Pipe Friction Guidelines

Typical Roughness ε (mm)

PVC/Plastic: 0.0015–0.007

Steel: 0.046

Concrete: 0.3–3.0

Flow Regime

Laminar: Re < 2300 → f=64/Re

Transition: 2300–4000

Turbulent: Re > 4000 → Moody/Colebrook