Similar to the development of flow at the entrance of the [http://альтернатив.рф/news/2017-12-29/raschet-konomicheskogo-ffekta-pri-primenenii-stekloplastikovykh- pipe], the flow velocity profile changes before the exit of a pipe. The exit length is much shorter than the entrance length, and is not significant at moderate to high Reynolds numbers.
Hydraulic exit length for laminar flows may be approximated as:
where
*  is the exit length,
*  is the pipe inner diameter, and
*  is the Reynolds number.