Sump Pump Size Calculator
Who it's for: Plumbing contractors, service technicians, and homeowners evaluating sump replacement.
Calculator Inputs
Quick Summary
- Built for: Plumbing contractors, service technicians, and homeowners evaluating sump replacement.
- Key outputs: Required planning flow (GPM), Suggested HP class, and more.
- Use this page for early planning estimates before final code and manufacturer verification.
Inputs
- Estimated inflow (GPM)
- Safety factor (%)
- Total dynamic head (ft)
Outputs
- Required planning flow (GPM)
- Suggested HP class
- Pump-curve verification note
How this calculator estimates results
- Scales estimated inflow by user-selected safety factor to produce required planning flow.
- Maps required flow to a simple HP class table for head <= 10 ft.
- Applies a one-class increase when dynamic head exceeds 10 ft to reflect extra pumping demand.
Cross-check assumptions with Water Pressure Drop Calculator for a more complete planning workflow.
Common ranges and tips
- Confirm inflow assumptions from site observations or historical pump-cycle data when possible.
- Use conservative head estimates that include vertical lift and friction losses.
- Always verify final pump selection on manufacturer pump curves at your actual duty point.
- Review backup power and alarm strategy for high-consequence installations.
Related Calculators
FAQ
Required flow is inflow multiplied by the safety factor, giving a planning target above expected normal inflow.
Higher head typically reduces delivered flow, so the estimator shifts one class up when head is above a simple threshold.
No. Final model selection must be validated against manufacturer curves and project-specific head calculations.
Use a factor that matches project risk and uncertainty; too little margin can undersize, while too much can overshoot cost and cycling behavior.
Disclaimer: Use results for planning only. Final design and installation decisions must follow local code and manufacturer documentation.
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