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Civil Engineering

Manning’s Formula Calculator

Civil Engineering

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Manning’s Formula

Equation and meaning

\[V = \frac{1}{n} \cdot {R}^{\frac{2}{3}} \cdot {S}^{\frac{1}{2}}\]

Use this equation when the shown variables describe your problem. Keep all inputs in compatible units; the calculator converts them to SI internally before solving.

Variables in this formula

n — N
Enter this value unless it is the selected unknown.
R — Resistance
Electrical resistance SI unit: Ω
S — S
Enter this value unless it is the selected unknown.
V — Voltage
Voltage SI unit: V

How to use this calculator

  1. Leave one value emptyThe empty field is automatically treated as the unknown.
  2. Enter known values and unitsChoose N, kgf, dyn, SI or another compatible unit when available.
  3. Review the automatic answerThe result appears immediately and is substituted back into the formula to check the residual.
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