When to use this calculator
Find ideal liquid outlet speed under a chosen hydrostatic head. Large open reservoir, negligible free-surface speed and no viscous or discharge losses.
Explore the fluids & flow calculators for other questions in this topic. For a related calculation, use the Volumetric Flow Rate Calculator: Calculate volumetric flow from cross-sectional area and average velocity.
PUTTING IT INTO PRACTICE
Torricelli Efflux Speed: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Liquid head above outlet (m) | 5 |
| Gravity (m/s²) | 10 |
| Result | 10 m/s |
- Check the input labels and enter the example values above.
- Apply the relationship: Ideal exit speed = √(2gh).
- The result is 10 m/s, rounded for display.
How to interpret your result
Large open reservoir, negligible free-surface speed and no viscous or discharge losses.
Use the fluid properties at the relevant conditions. Gauge pressure is measured relative to a reference and differs from absolute pressure. Average flow velocity and characteristic length must match the geometry being modelled.
Frequently asked questions
Should hydrostatic pressure be added to atmospheric pressure?
Add the surface absolute pressure when an absolute result is needed. The basic liquid-column calculation alone gives the pressure increase with depth.
When is the torricelli efflux speed calculator useful?
Find ideal liquid outlet speed under a chosen hydrostatic head. Large open reservoir, negligible free-surface speed and no viscous or discharge losses.
How do I use the torricelli efflux speed calculator?
Enter liquid head above outlet (m), gravity (m/s²). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Ideal exit speed = √(2gh).
What should I check before using the result?
Large open reservoir, negligible free-surface speed and no viscous or discharge losses.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see OpenStax: fluids, density and pressure ↗. This is a topic reference, not an external review or endorsement of this tool.
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