The friction head can be related to the pressure loss due to friction by dividing the pressure loss by the product of the acceleration due to gravity and the density of the fluid.  Accordingly, the relationship between the friction head and the Fanning friction factor is:
where:
* is the friction loss (in head) of the pipe.
* is the Fanning friction factor of the pipe.
* is the flow velocity in the pipe.
* is the length of pipe.
* is the local acceleration of gravity.
* is the pipe diameter.