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Weir Flow Calculator

Calculate the volumetric flow rate of water passing over a weir based on weir width, upstream head, and weir type. Used by civil engineers and hydrologists to measure or control open-channel flow in rivers, canals, and water treatment plants.

Weir Width (m)

Head Above Weir (m)

Discharge Coefficient

Fill in the required fields to see your result.

Fluid Mechanics

Weir Flow Calculator

Calculate volumetric flow rate over rectangular, triangular, or trapezoidal weirs from the head of water above the weir crest. Used in irrigation canals, wastewater treatment, and stream gauging.

Weir Width/Length (m)

Head Over Weir (m)

Weir Type

Discharge Coefficient

End Contractions

Fill in the required fields to see your result.

Key differences

	Weir Flow Calculator	Weir Flow Calculator
Category	Fluid Mechanics	Fluid Mechanics
Inputs required	3	5
Result	Flow Rate (m³/s)	Flow Rate (m³/s)
What it does	Calculate the volumetric flow rate of water passing over a weir based on weir width, upstream head, and weir type. Used by civil engineers and hydrologists to measure or control open-channel flow in rivers, canals, and water treatment plants.	Calculate volumetric flow rate over rectangular, triangular, or trapezoidal weirs from the head of water above the weir crest. Used in irrigation canals, wastewater treatment, and stream gauging.