Fixture Flow Rate Calculator
Who it's for: Plumbing designers, estimators, and inspectors.
Calculator Inputs
Quick Summary
- Built for: Plumbing designers, estimators, and inspectors.
- Key outputs: Total connected GPM, Adjusted peak GPM, and more.
- Use this page for early planning estimates before final code and manufacturer verification.
Inputs
- Fixture counts by type
- Flow assumptions per fixture
- Diversity factor
Outputs
- Total connected GPM
- Adjusted peak GPM
- Fixture demand summary
How this calculator estimates results
- Multiplies each fixture count by a typical assumed fixture flow rate for planning purposes.
- Sums all fixture subtotals to calculate connected flow demand.
- Applies a user-selected diversity factor to estimate likely peak simultaneous flow.
Cross-check assumptions with Pipe Size Calculator for a more complete planning workflow.
Common ranges and tips
- Use real fixture schedules where available to refine assumptions.
- Higher diversity factors represent more simultaneous usage and increase estimated peak demand.
- Use connected and peak flow together when planning pipe sizing checks.
Related Calculators
FAQ
Connected flow assumes everything runs at once, while peak flow applies diversity to estimate likely simultaneous demand.
Not always. This estimator uses simplified average assumptions, so real draw profiles may vary during actual operation.
Start with a conservative value for your building type, then compare scenarios to understand demand range before final design.
No. Use this as a planning tool only, then verify final sizing with applicable code methods and local requirements.
Disclaimer: Use results for planning only. Final design and installation decisions must follow local code and manufacturer documentation.
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