Required Pipe Diameter Calculator

Calculate the required pipe diameter for full flow using Manning’s equation:
\[ d = \left( \frac{n\,4^{\frac{5}{3}}\,Q}{\pi\,\sqrt{S}} \right)^{\frac{3}{8}} \]

* Enter the flow rate \(Q\) (ft³/s), Manning’s roughness coefficient \(n\), and channel slope \(S\) (ft/ft).

Step 1: Enter Parameters

Flow Rate, \( Q \) (ft³/s):

Example: 20 ft³/s

Manning’s Roughness Coefficient, \( n \):

Example: 0.015

Channel Slope, \( S \) (ft/ft):

Example: 0.01 ft/ft

Step 1: Enter Parameters

Calculated Pipe Diameter