About the Weir Discharge Calculator Online Free Tool

The Weir Discharge Calculator Online Free Tool estimates flow over rectangular and V-notch weirs from discharge coefficient, head, and geometry. It is useful for quick hydraulic measurement and small-structure checks.

How to Use the Weir Discharge Calculator Online

1. Enter the required inputs in the fields above using the units shown on the labels.
2. Select any mode, shape, or method options so the calculation matches your scenario.
3. Run the calculation and review the result summary in the output panel.
4. Check the units, assumptions, and project requirements before using the result outside preliminary review.

Choosing Options Correctly

Head is measured over the crest in meters. The discharge coefficient must be between 0 and 1. Use the weir type selector to show the matching width or V-notch angle field.

Common Use Cases

• Estimate discharge over a rectangular sharp-crested weir.
• Estimate V-notch flow from notch angle and head.
• Compare flow sensitivity to head or discharge coefficient.

Quick FAQ

Which weirs are supported?
Use it for the weir shape/options shown in the tool, such as rectangular or V-notch cases.

What head should I enter?
Use the upstream head over the crest, measured at the correct location away from drawdown effects.

Does it handle submerged flow?
No. Submergence, approach velocity, nappe condition, and calibration may require corrections.

Can this be used for flow measurement?
Use it for estimates only unless the weir is built, installed, and calibrated to the required standard.