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Hydraulic Radius and Manning Flow Velocity Calculator

v = (1/n) × R^(2/3) × S^(1/2) — Manning equation.

Calculates hydraulic radius, flow velocity, and volumetric flow rate for open-channel or pipe-full flow using Manning's equation. Useful for culvert, canal, and pipe design.

Priya Venkatesan By Priya Venkatesan
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

R = A/P_wet; v = R^(2/3) × S^(1/2) / n; Q = v × A

In depth

Calculates hydraulic radius, flow velocity, and volumetric flow rate for open-channel or pipe-full flow using Manning's equation. Useful for culvert, canal, and pipe design.