**Fanning and Moody friction factors**

## What is the difference ?

## How to calculate Moody factor from Fanning factor ?

1.
Introduction

2. Relation in between Fanning and Moody friction factors

**1. What is the difference in between Fanning and Moody friction
factors ?**

The friction factor is used to calculate the pressure drop due to the flow of a
fluid in a pipe. It represents the interaction in between the fluid
and the pipe. **One must be extremely careful when consulting
literature for correlations as the nature of the friction factor
used in not always very well apparent. It can indeed be expressed
according to Moody or to Fanning, with a factor 4 in between both
coefficients.**

**Figure 1 : Friction at the pipe
interface**

**2. Relation in between Fanning and Moody friction factors**

Moody
factor can be calculated from Fanning factor with the following
formula :

**f**_{Moody} = 4*f_{Fanning}

f_{Moody} = Moody's friction factor

f_{Fanning} = Fanning's friction factor

Note that Moody's friction factor is sometimes called Darcy or
Darcy-Weisbach friction coefficient.