Pipe Sizing Calculator
Determine the optimal pipe size for your water supply system based on flow rate and velocity limits.
How to Use This Calculator
This calculator helps you determine the correct pipe size for water supply lines based on the required flow rate and maximum allowable velocity.
Input Parameters
- Flow Rate (GPM): The peak water demand in gallons per minute. Use the Fixture Units Calculator to determine this value.
- Pipe Material: Different materials have different internal diameters and recommended velocity limits.
- Max Velocity: Auto-filled based on material. Higher velocities cause noise and pipe erosion.
- Pipe Length: Optional. Enter to calculate estimated pressure drop.
Code Reference
Per IPC Section 604.3, water velocity should not exceed the following limits:
- Copper, PEX, CPVC, PVC: 8 ft/s maximum
- Steel, Galvanized: 5-6 ft/s maximum (varies by age)
Formula Used
D = √(4 × Q / (π × V))
Where:
D = Pipe diameter (ft)
Q = Flow rate (ft³/s)
V = Velocity (ft/s)
Where:
D = Pipe diameter (ft)
Q = Flow rate (ft³/s)
V = Velocity (ft/s)