Manning's Equation Calculator
Units
US (ft, cfs)
SI (m, m³/s)
Manning's n
—
Area, A
ft²
Hyd. radius, R
ft
Slope, S
ft/ft
Velocity, V
—
ft/s
Discharge, Q
—
cfs
$$ V = \frac{k}{n} R^{2/3} S^{1/2}, \quad Q = V \cdot A $$
via
PE-Calc — Manning's Equation