Venturi Meter Flow Rate Calculator

About this calculator

A venturi meter measures flow rate by narrowing a pipe to a throat section, which forces the fluid to speed up and, by Bernoulli's principle, drop in pressure — the bigger that pressure drop, the faster the fluid is moving. The flow rate is recovered from Q = Cd × A₂ × √(2ΔP / (ρ(1−(A₂/A₁)²))), where A₁ and A₂ are the inlet and throat areas, ΔP is the measured pressure differential, ρ is fluid density, and Cd is a discharge coefficient (typically 0.95-0.99) that corrects for the small energy losses a real venturi has that the idealized Bernoulli equation ignores.

This calculator takes your venturi's inlet and throat diameters, the measured pressure drop, fluid density and discharge coefficient, and returns the volumetric flow rate. Process and chemical engineers monitoring flow in a pipeline, HVAC and plumbing engineers sizing metering devices, and instrumentation technicians calibrating a venturi flow meter use it because venturi meters are prized for measuring flow with very little permanent pressure loss compared to an orifice plate, making them a common choice for permanent installations.