Hydraulic Radius Calculator

Find the hydraulic radius from flow area and wetted perimeter.

Flow area

Wetted perimeter

Hydraulic radius 0.25

Formula: R = A ÷ P

Step-by-step with your numbers:

1. Values used:

2. Flow area = 0.5

3. Wetted perimeter = 2

5. Hydraulic radius = Flow area / Wetted perimeter = 0.5 / 2 = 0.25

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The hydraulic radius characterizes channel flow geometry.

The math behind it

R = flow area ÷ wetted perimeter. It feeds into Manning's and Darcy's equations.

A = 0.5 m², P = 2 m → R = 0.25 m.

What is the wetted perimeter?

The length of the channel boundary in contact with the fluid.