Weir Flow Calculator

Name: Weir Flow Calculator
Availability: InStock
Author: Daniel Agrici

Calculate flow rate over rectangular, V-notch, and Cipolletti weirs from head measurement. Enter values for instant results with step-by-step formulas.

Reviewed by Daniel Agrici, Founder & Lead Developer

Formula

Rectangular: Q = (2/3)Cd × L × √(2g) × H^(3/2) | Triangular (90°): Q = (8/15)Cd × √(2g) × tan(θ/2) × H^(5/2)

Francis formula for rectangular weirs (Cd≈0.62). Kindsvater-Shen for triangular (V-notch) weirs. g = 9.81 m/s².

Worked Examples

Example 1: Rectangular weir

Problem:L=2m, H=0.3m

Solution:Q = 0.667×0.62×2×√19.62×0.3^1.5 = 0.596 m³/s

Result:0.596 m³/s

Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy