01
The purpose
What does this calculator estimate?
Size a cartridge filter to your flow so it cleans well and goes longer between hose-downs.
Pumps & Filtration · C10
Pool Cartridge Filter Sizing Calculator
Size a cartridge filter to your flow so it cleans well and goes longer between hose-downs.
Measure the inputsOversize generously — a big cartridge filter can go months between cleanings.
Read the full resultCartridge filters waste no backwash water, ideal for drought areas and water restrictions.
Check the boundaryKeep a spare cartridge so you can swap and clean the dirty one at leisure.
Useful forPumps & FiltrationPlanningComparisonVerification
Live calculation
Cartridge filter inputs
✓ Checked May 2026
Enter volume and pump flow.
Calculated result
—
Enter the required values to calculate.
Enter the known values. Let the engine handle the calculation.
✓ Formula checked↻ Live result○ No account needed
Planning estimate only. Confirm product labels, equipment specifications, qualified-professional advice and local requirements before acting.
The result, explained
Use the Pool Cartridge Filter Sizing Calculator result with context.
Size a cartridge filter to your flow so it cleans well and goes longer between hose-downs.
02
The tool
What information does it use?
- Pool volume: enter a measured or verified value
- Pump flow rate: Your pump's GPM.
03
The method
How to use this calculator
- Pool volumeEnter the value you can verify.
- Pump flow rateYour pump's GPM.
04
The relationship
The formula in plain English
Required cartridge area = Pump GPM ÷ 0.375 (max GPM per sq ft)
Cartridge filters use no backwash water — clean by hosing the element. Bigger = longer between cleanings.05
Worked through
A worked example: 60 GPM pump
- Required area = 60 ÷ 0.375 = 160 sq ft
- 160 sq ft → 200 sq ft (next standard)
- Larger area = longer between cleanings
| Pump flow | Min area | Recommended size | Cleaning interval |
|---|---|---|---|
| 40 GPM | 107 sq ft | 150 sq ft | Monthly+ |
| 60 GPM | 160 sq ft | 200 sq ft | 1–2 months |
| 80 GPM | 213 sq ft | 300 sq ft | 2–3 months |
| 100 GPM | 267 sq ft | 300 sq ft | Monthly |
| 140 GPM | 373 sq ft | 420 sq ft | 1–2 months |
06
Why it matters
How the result supports the next decision
Oversize generously — a big cartridge filter can go months between cleanings.
Cartridge filters waste no backwash water, ideal for drought areas and water restrictions.
07
Good inputs
Improve the estimate before relying on it
- Oversize generously — a big cartridge filter can go months between cleanings.
- Cartridge filters waste no backwash water, ideal for drought areas and water restrictions.
- Keep a spare cartridge so you can swap and clean the dirty one at leisure.
- Soak cartridges in filter cleaner once a year to remove oils a hose can't.
- They filter finer than sand (down to ~10–20 microns) for clearer water.
08
The boundary
How to interpret the result
Measurements, equipment specifications, site conditions and local requirements can change the practical result.
The engine reports invalid inputs and safety warnings beside the result. Resolve those messages before using the estimate.
09
Before acting
What should override this estimate?
- Measured site conditions and current test results
- Product labels and manufacturer specifications
- Qualified-professional advice and applicable local codes
10
Common questions
Frequently asked questions
How do I size a cartridge filter?
Divide your pump's flow rate by 0.375, the maximum recommended GPM per square foot of cartridge media, to find the minimum total area. Then pick the next standard size up. Generous sizing is the norm with cartridge filters because more area means cleaner water and far longer intervals between cleanings.
Why are cartridge filters sized so large?
Cartridge media filters at a low flow per square foot — about 0.375 GPM — so adequate flow requires a lot of surface area. A 60 GPM pump needs roughly 160 square feet. The large area is a feature: it lets the filter capture fine debris while going months between cleanings.
Do cartridge filters save water?
Yes, significantly. They're cleaned by removing the element and rinsing it with a hose, using a few gallons rather than the dozens or hundreds a backwash consumes. In water-restricted regions this is often the deciding reason to choose cartridge over sand or DE.
How often do I clean a cartridge filter?
It depends on size relative to your pool's debris load, but a properly oversized cartridge filter often goes one to three months between cleanings. Clean when the pressure gauge rises about 8 PSI over the clean reading, just as with other filter types.
Are cartridge filters better than sand?
They filter finer — down to about 10 to 20 microns versus sand's 20 to 40 — and use no backwash water, but cartridges cost more to replace and require hands-on cleaning. For clarity and water conservation, cartridge wins; for lowest maintenance effort and cost, sand competes well.
What size cartridge filter for a 60 GPM pump?
At least 160 sq ft (60 ÷ 0.375); choose the next standard size up, often 200 sq ft.
How many microns does a cartridge filter remove?
Roughly 10–20 microns, finer than sand but coarser than DE.
Do cartridge filters backwash?
No — you remove and hose off the cartridge, saving the water a backwash would use.
Primary sources
Use the result with current guidance.
These official references support safe planning context. Product labels, local requirements and qualified-professional advice take priority over a general calculator estimate.