Manning Flow Calculator

Calculate open channel flow velocity and discharge using Manning's equation online. Supports rectangular, trapezoidal, and circular channels — free hydraulic calculator

RectangularTrapezoidalCircular

Manning's n

Channel Geometry

Channel Slope S

Bottom Width b (m)

Water Depth y (m)

Results

Discharge Q

3.0648

m³/s

Velocity V

1.5324

m/s

Hydraulic Radius R

0.5000

Flow Area A

2.0000

m²

Wetted Perimeter P

4.0000

Froude Number Fr

0.489

Subcritical (Fr < 1)

V = (1/n) × R^(2/3) × S^(1/2)

Q = V × A

R = A / P

Fr = V / √(g × D_h)