Venturi Meter Flow Rate Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 26, 2026Venturi Meter Flow Rate Calculator
A venturi meter measures flow rate by narrowing a pipe to a smaller throat, causing a predictable, measurable pressure drop that scales directly with flow rate.
The Formula
Q = Cd × A2 × √(2ΔP / (ρ × (1-(A2/A1)²)))
Worked Example
A venturi with 0.98 discharge coefficient, 20 cm² throat, 80 cm² upstream pipe, 15 kPa pressure difference, water (1000 kg/m³): Q ≈ 11.09 L/s.
How to Use This Calculator
- Enter the discharge coefficient (typically 0.95-0.99 for a well-made venturi).
- Enter throat area and upstream pipe area.
- Enter the measured pressure difference and fluid density.
Unlike a sharp-edged orifice, a venturi's gradual contraction and expansion causes far less permanent pressure loss for the same measurement accuracy - the trade-off is a bulkier, more expensive meter.