Hydraulics & drainage · Pipes & hydraulic structures

Orifice outlet calculator

Discharge of an orifice under head and the orifice size for a target flow.

Standard: Torricelli Q = Cd A √(2gh)

Inputs in the worked example

The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.

Diagram for the worked example

Area = PI()*(130/1000)^2/4 = 0.013273 m²
Q = 0.6*0.013273*SQRT(2*9.81*1.2)*1000 = 38.643 L/s
Diameter for target flow = SQRT(4*40/1000/(0.6*SQRT(2*9.81*1.2))/PI())*1000 = 132.26 mm

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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.