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Fluid Mechanics / Flow Measurement

Venturi Flow Calculator

Enter inlet diameter, throat diameter, and differential pressure to get flow rate through a venturi meter.

Flow Rate
L/s

How this is calculated

Q = Cd · A2 / √(1−β⁴) · √(2·ΔP/ρ),   β = D2/D1
Enter values above to see the worked calculation.

When to use this calculator

A venturi meter accelerates flow through a narrowing throat, and the pressure drop between inlet and throat gives flow rate. Compared to an orifice plate, a venturi recovers most of its pressure downstream (permanent loss is much lower), at the cost of a bulkier, more expensive fitting. Cd typically runs 0.95–0.99 for a well-machined venturi.

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