Flow Discharge Coefficient Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 26, 2026Flow Discharge Coefficient Calculator
No real flow restriction achieves the exact flow rate an idealized Bernoulli-based calculation predicts - discharge coefficient captures exactly how much real flow falls short of that theoretical ideal.
Formula: Cd = Qactual / Qtheoretical
Example: a device passing 0.85 units of flow against a theoretical prediction of 1.0 has a discharge coefficient of 0.85.
How to Use This Calculator
- Enter the actual measured (or manufacturer-rated) flow rate.
- Enter the theoretical flow rate from an ideal flow equation, in the same units.
Typical values range from around 0.6 for sharp-edged orifices (where flow contracts sharply just past the opening, called a vena contracta) up to nearly 0.98 for smooth, well-designed venturi meters - discharge coefficients are usually determined experimentally for a specific device rather than calculated from first principles.