How to use the venturi calculator
Prepare the values for this calculation
Calculate ideal incompressible Venturi flow from pressure drop, density and two cross-sectional areas. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Upstream-minus-throat pressure ΔP (Pa): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Fluid density ρ (kg/m³): enter a value at least 1e-12. Use the unit named in the label or selected above. Do not leave this required field blank.
- Upstream area A₁ (m²): enter a value at least 1e-12. Use the unit named in the label or selected above. Do not leave this required field blank.
- Throat area A₂ (m²): enter a value at least 1e-12. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Ideal volumetric flow first. With the unchanged example inputs, it is 0.051639777949 m³/s. Interpret it using the formula and assumptions on this page.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Upstream-minus-throat pressure ΔP (Pa) from 10000 to 11000. The resulting Ideal volumetric flow is 0.054160256031 m³/s. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Venturi Calculator formula
Q=√[(2ΔP/ρ)/(1/A₂²−1/A₁²)].
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Upstream-minus-throat pressure ΔP (Pa) | minimum 0 | 10000 |
| Fluid density ρ (kg/m³) | minimum 1e-12 | 1000 |
| Upstream area A₁ (m²) | minimum 1e-12 | 0.02 |
| Throat area A₂ (m²) | minimum 1e-12 | 0.01 |
Worked example
Using the example inputs above, the ideal volumetric flow is 0.051639777949 m³/s.
- Ideal volumetric flow
- 0.051639777949 m³/s
Results and assumptions
Ideal horizontal incompressible Venturi without losses.
Fix an input or unexpected result
Upstream-minus-throat pressure ΔP (Pa) is required. Enter upstream-minus-throat pressure δp (pa) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.