Garden & Outdoor calculator
What Pool Pump Size Do I Need?
Use pool volume, target turnover time hours, flow derating factor to find pool pump rated-flow requirement.
Enter your measurements
What Pool Pump Size Do I Need uses pool volume, target turnover time hours, flow derating factor and the other configured measurements to return pool pump rated-flow requirement with a formula written specifically for this tool.
- Pool volume — Required
- Target turnover time hours — Required
- Flow derating factor — Required
Pool pump rated-flow requirement
Enter the measurements above to calculate pool pump rated-flow requirement.
How the calculation works
V17 calculation: requiredActualFlow=poolVolume/targetTurnoverHours/3600; requiredRatedFlow=requiredActualFlow×systemLossFactor. The result is reported as Pool pump rated-flow requirement.
Worked example
Example: Pool volume = 30000 L; Target turnover time hours = 2 h; Flow derating factor = 1.2. Result: Required Rated Flow = 5 L/s; Required Actual Flow = 4.17 L/s.
Before you decide
Use measured dimensions rather than nominal labels. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what pool pump size do i need, the limiting result on this page is pool pump flow rate.
Direct measurement/geometry calculation. No external reference is required for the arithmetic itself; the result is derived only from the user-entered measurements and the formula stored in calculationLogicJson.
Frequently asked questions
What does the Pool Pump Size calculator tell me?
It returns pool pump flow rate from the measurements entered on this page. The calculation is specific to pool pump size, so the result should be compared with the exact product or specification you are considering.
Which measurements should I take for pool pump size?
Measure pool volume, target turnover time hours, flow derating factor. Use clear, usable dimensions rather than nominal room or product labels.
Should I round the pool pump flow rate?
Keep the calculated value for comparison, then choose a real product that meets or stays within the returned pool pump flow rate while allowing for the clearances, tolerances or ratings shown by its manufacturer.