 # Fanning and Moody friction factors

## 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 :

### fMoody = 4*fFanning

fMoody = Moody's friction factor

fFanning = Fanning's friction factor

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