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Velocity to Flow Rate

Flow meter users who know what flow rate they need to measure can use this calculator to determine if a flow meter is capable of measuring that flow rate based on the manufacturer’s published velocity measurement specifications. Flow meter technologies such as differential pressure, magnetic, thermal, turbine, ultrasonic and vortex all measure flow rate as a function of fluid velocity. Any flow meter employing one of these technologies will have a published specification for the range of velocities that it is capable of measuring.  By using the flow continuity equation in this section Where: Flow (Q) =V (flow velocity) X A (cross sectional area of the measurement location), engineers can determine both the velocity and/or flow range for any flow meter which employs one of these technologies.

If you need a recommendation for a difficult-to-measure flow application, please feel free to contact SmartMeasurementTM’s U.S. offices at 1-866-404-5415 for assistance. Our team of application engineers would be happy to review your application and recommend one or more suitable technologies at industry-leading prices.


Average flow velocity, V 

Cross-section area for pipes, ducts, or others (pick one):


Inner diameter of pipe, di


Width and depth of duct, xi × yi


Cross section area, Ai


Average flow velocity, v = Q / A = 0.212207