Pipe Size Calculator
Find the right water supply pipe size for your project
Sum of WSFU
Static pressure at meter
From meter to farthest fixture
Main Supply Line
—
inches
Branch Lines
—
inches
Peak Flow Rate
—
GPM
Disclaimer: Results are estimates based on standard formulas. Not a substitute for professional advice from a licensed contractor, engineer, or architect. Verify all calculations before making purchasing or construction decisions.
How to Use This Calculator
Our pipe size calculator follows UPC and IPC guidelines to recommend the right pipe diameter.
- Add up WSFU for all fixtures
- Measure static pressure at meter
- Determine longest pipe run
- Enter specifications
- Consider future additions
AI Insights
Smart analysis for your project
Smart Estimates
Our AI cross-references material costs, regional pricing, and project complexity for more accurate estimates.
Waste Optimization
AI-calculated waste factors based on project type, not flat percentages. Saves 5-15% on material costs.
Best Practices
Recommendations derived from building codes, contractor data, and thousands of completed projects.
Calculation Formula
Based on UPC/IPC tables:
Flow rate from WSFU conversion
Pipe size from flow rate x pressure x length
Frequently Asked Questions
What size pipe for a main water line?
Most homes use 3/4" or 1" copper/PEX for main supply. Size depends on fixtures and pressure.
What are WSFU?
Water Supply Fixture Units: bathroom faucet = 1, shower = 2, toilet = 2.5, kitchen sink = 1.5, washing machine = 4.