Well Pump Sizing Calculator
Enter household demand, static water level, and pipe details to calculate the required well pump flow rate and horsepower.
Well & Household Details
Fill in your well details and click Calculate Pump Size.
Required Flow
—
GPM
Total Head
—
feet (TDH)
Min. Pump HP
—
horsepower
Total Dynamic Head Breakdown
Pump Type Recommendation
Standard Pump Sizes
| HP | Typical Max GPM | Best For |
|---|
Summary
Enter household demand, static water level, and pipe details to calculate the required well pump flow rate and horsepower.
How it works
- Enter the number of bathrooms and other fixture groups — the tool converts these to a peak demand in GPM using standard fixture unit values.
- Enter the static water level (depth from ground surface to water when the pump is off).
- Enter the drawdown — how far the water level drops under pumping. Total pump setting depth = static level + drawdown.
- Enter the pipe run length from pump to pressure tank and the pipe diameter. Pipe friction is computed using the Hazen-Williams formula.
- Total Dynamic Head (TDH) = pump setting depth + pressure head (PSI × 2.31) + friction head loss.
- Minimum HP is derived from TDH × GPM ÷ 3,960 ÷ pump efficiency (assumed 0.60). Select the next standard HP size up.
Use cases
- Size a replacement submersible well pump for a residential home.
- Verify that an existing pump can meet demand after adding bathrooms or fixtures.
- Estimate pump requirements during new construction before drilling.
- Compare 1/2 HP vs 3/4 HP vs 1 HP options for a shallow or deep well.
- Determine whether a single-line jet pump or a submersible is appropriate for your well depth.
Frequently Asked Questions
Last updated: 2026-07-23 ·
Reviewed by Nham Vu