Garden & Outdoor calculator
What Pool Filter Size Do I Need?
Find pool filter area/capacity from pool system flow rate, allowed filter flow per area, and filter area reserve fraction.
Enter your measurements
The key to what pool filter size do i need is having the right measurements: pool system flow rate, allowed filter flow per area, and filter area reserve fraction. This minimum-capacity calculation uses them to return pool filter area/capacity in a form you can compare directly.
- Pool system flow rate — Required
- Allowed filter flow per area — Required
- Filter area reserve fraction — Required
Pool filter area/capacity
Enter the measurements above to calculate pool filter area/capacity.
How the calculation works
The engine follows this rule: minimumFilterArea=requiredFlow/filterLoadingRate×(1+reserve). It returns pool filter area/capacity from the configured inputs.
Worked example
Example: Pool system flow rate = 0.8 L/s; Allowed filter flow per area = 0; Filter area reserve fraction = 15%. Result: Minimum Filter Area = 4.6 m².
Before you decide
Recheck the limiting measurement before purchase or installation. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what pool filter size do i need, the limiting result on this page is pool filter area/capacity.
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 Filter Size calculator tell me?
It returns pool filter area/capacity from the measurements entered on this page. The calculation is specific to pool filter size, so the result should be compared with the exact product or specification you are considering.
Which measurements should I take for pool filter size?
Measure pool system flow rate, allowed filter flow per area, filter area reserve fraction. Use clear, usable dimensions rather than nominal room or product labels.
Should I round the pool filter area/capacity?
Keep the calculated value for comparison, then choose a real product that meets or stays within the returned pool filter area/capacity while allowing for the clearances, tolerances or ratings shown by its manufacturer.