Free Online Manning Pipe Head Loss Calculator

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Manning Formula Head Loss at Given Full Flow

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Printable version (reload the page to return to the normal view)

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Notes

This calculator does not model the pipe profile between the two ends.

If the HGL goes below the top of the pipe at any point, this calculation may not be valid.

For an open inlet (culvert) condition, it is necessary to check for inlet control conditions.

1. The upstream HGL must be above the upstream normal depth flow elevation (and higher than the pipe!).

2. The headwater of a culvert is better represented by the upstream EGL than the upstream HGL.

3. See my 2-minute tutorial for simple standard culvert headwater calculations using HY-8, the free culvert program from the U.S. Federal Highway Administration.

4. This page solves the outlet control case only: a pipe flowing full, where the downstream conditions set the head. Culvert design is the job of deciding whether inlet control or outlet control governs, so use HY-8 whenever either one could.