Venturi Flow Meter Calculator
Calculate incompressible meter flow from throat/upstream diameters, measured differential pressure and entered coefficient.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Combine equal-elevation Bernoulli pressure change and continuity, applying your entered meter coefficient.
Q=Cd A₂√(2 ΔP/(ρ(1−β⁴))); β=d₂/d₁
Worked example
A 50 mm upstream bore and 25 mm throat give β=0.5 and 1−β⁴=0.9375. Doubling differential pressure multiplies the modeled flow by √2.
Assumptions and input details
Throat must be smaller than upstream. Same-elevation liquid pressure taps, no compressibility correction, cavitation, coefficient calibration or meter-standard compliance. Differential pressure is not permanent pressure loss.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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