Flow Rate Calculator
Calculate volumetric flow rate based on pipe diameter and fluid velocity using the continuity equation for accurate system design.
Internal diameter of the pipe
Average flow velocity in the pipe
Calculation Results
Enter your parameters and click "Calculate Flow Rate" to see results
How to Use the Flow Rate Calculator
Input Parameters
- Pipe Diameter: Internal diameter of the pipe (mm or inches)
- Fluid Velocity: Average flow velocity through the pipe (m/s or ft/s)
Calculation Results
- Volumetric Flow Rate: Flow rate in L/s or GPM
- Alternative Units: Flow rate in m³/h or GPH
- Pipe Cross-Section: Cross-sectional area of the pipe
About the Calculation
This calculator uses the fundamental continuity equation from fluid mechanics: Q = A × V, where Q is the volumetric flow rate, A is the cross-sectional area of the pipe (π × D² / 4), and V is the average fluid velocity. This relationship is essential for sizing pipes, pumps, and flow measurement devices in water supply, HVAC, chemical processing, and irrigation systems.
Common Applications
- • Water supply system design
- • HVAC piping calculations
- • Pump selection and sizing
- • Flow meter verification
- • Chemical process piping
- • Irrigation system design
Important Considerations
The calculation assumes fully developed, steady-state flow. Actual flow rates may vary due to turbulence, entrance effects, and local flow disturbances. For critical applications, verify flow rates using calibrated flow measurement instruments. Always consult applicable codes and standards for your specific application.