Pipe Friction Factor Calculator (Colebrook-White / Haaland)

Pipe Friction Factor Calculator (Colebrook-White / Haaland) | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Math & Numbers
Input types: number, select
Output type: json
Sample coverage: 4
API ready: Yes

Overview

The Pipe Friction Factor Calculator computes the Darcy friction factor from Reynolds number, pipe roughness, and internal diameter. It uses f=64/Re for laminar flow and Colebrook-White iteration for higher Reynolds numbers, while also returning a Haaland estimate for comparison.

When to use

Estimate the Darcy friction factor for a pipe-flow calculation.
Compare iterative Colebrook-White and explicit Haaland results for turbulent flow.
Check how pipe roughness, diameter, and Reynolds number affect the flow regime and relative roughness.

How it works

1Enter a positive Reynolds number, absolute roughness, and internal pipe diameter.
2Select roughness and diameter units: m, mm, or µm for roughness, and m, cm, or mm for diameter.
3Choose Auto, Colebrook (iterative), or Haaland (explicit) as the calculation method.
4Review the Darcy friction factor, Haaland cross-check, relative roughness, flow regime, effective method, and iteration count.

Use cases

Pipe-flow and fluid-mechanics calculations requiring a Darcy friction factor.
Hydraulic comparisons between smooth and rough pipes using relative roughness.
Engineering checks that compare Colebrook-White results with the Haaland approximation.

Examples

1. Commercial-steel pipe at Re=100,000

Fluid systems engineer

Background

An engineer needs the Darcy friction factor for a commercial-steel pipe with known roughness and diameter.

Problem

Calculate the turbulent friction factor and compare the iterative result with the Haaland approximation.

How to use

Enter Reynolds number 100000, roughness 0.0457 mm, diameter 0.05 m, select Auto, and use 6 decimal places.

Re=100000; ε=0.0457 mm; D=0.05 m; Method=Auto; Decimal places=6

Outcome

The tool reports turbulent flow, relative roughness ε/D=0.000914, Colebrook friction factor f=0.021881, Haaland estimate 0.021664, and 10 iterations.

2. Smooth pipe at Re=10,000

Hydraulics student

Background

A student wants to verify the friction factor for a smooth pipe under turbulent-flow conditions.

Problem

Use zero roughness and compare the Colebrook-White result with the Haaland estimate.

How to use

Enter Reynolds number 10000, roughness 0 mm, diameter 0.1 m, select Auto, and use 6 decimal places.

FAQ

What does this calculator return?

It returns the Darcy friction factor, relative roughness, flow regime, effective method, and iteration count. A Haaland estimate is also provided as a cross-check.

Which formula is used for laminar flow?

For Re<2000, the calculator uses the closed-form relation f=64/Re.

How does Auto mode choose the method?

Auto uses the laminar formula when Re<2000 and Colebrook-White otherwise. The Haaland estimate is still reported for comparison.

Can I calculate friction for a smooth pipe?

Yes. Enter roughness as 0 to represent a perfectly smooth pipe.

What inputs are required?

Reynolds number, absolute roughness, and internal pipe diameter are required. Unit selections, method, and decimal places are optional.

Re=10000; ε=0 mm; D=0.1 m; Method=Auto; Decimal places=6

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Commercial-steel pipe at Re=100,000

2. Smooth pipe at Re=10,000

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