Darcy Friction Factor Calculator

Calculate Darcy-Weisbach friction factor (f) using Colebrook-White and Swamee-Jain explicit equations.

💡 Engineering Knowledge PrimerThe Darcy friction factor (f) dictates fluid friction loss against pipe internal walls. In turbulent flow, the Swamee-Jain explicit equation provides a precise mathematical approximation of the implicit Colebrook-White equation.

CALCULATION SCOPE — Deterministic calculation within the published assumptions. Independently verify all design decisions and project-specific code requirements.

INPUT DESIGN PARAMETERS (SI)

Reynolds Number (Re)[1]

Pipe Diameter (D)[mm]

Absolute Roughness (ε)[mm]

CALCULATED SPECIFICATION OUTPUT

Darcy Friction Factor (f)

💧

0.0184 1

Relative Roughness (ε/D)

0.0003 1

Technical Methodology & Engineering Principles

GOVERNING EQUATION

Swamee-Jain Equation: f = 0.25 / [ log10( (ε / (3.7 × D)) + (5.74 / Re^0.9) ) ]²

Assumptions & Scope

Turbulent flow regime in circular pipe.

Operating Range & Boundary

Use finite, physically meaningful inputs within the stated operating assumptions.

Peer Reference: Swamee, P. K., & Jain, A. K. (1976). Explicit equations for pipe-flow problems. Journal of the Hydraulics Division, ASCE, 102(5), 657-664.