Enter the flow rate and the pipe diameter into the calculator to determine the depth of flow in the pipe. This calculator assumes full pipe flow for a circular pipe.

Depth of Flow Formula

The following formula is used to calculate the depth of flow in a pipe.

DF = PD

Variables:

  • DF is the depth of flow in the pipe (feet)
  • PD is the pipe diameter (feet)

To calculate the depth of flow in a pipe, use the pipe diameter as the depth of flow for full pipe flow. For partial flow, a more complex formula involving the flow rate and pipe diameter would be needed.

What is Depth of Flow in a Pipe?

Depth of flow in a pipe refers to the vertical distance from the bottom of the pipe to the surface of the flowing water. It is an important parameter in hydraulic and civil engineering for designing and analyzing pipe systems. The depth of flow can vary depending on whether the pipe is flowing full or partially full.

How to Calculate Depth of Flow?

The following steps outline how to calculate the Depth of Flow in a Pipe.


  1. First, determine the flow rate (Q) in cubic feet per second.
  2. Next, determine the pipe diameter (PD) in feet.
  3. Next, gather the formula from above = DF = PD.
  4. Finally, calculate the Depth of Flow (DF) in feet.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

flow rate (Q) = 2 cubic feet per second

pipe diameter (PD) = 1 foot