Filter Size Calculator
Determines minimum filter surface area and type based on pump flow rate and NSF standards.
How it works
Filter Area = Pump GPM ÷ Flow Rate per Sq FtSand: 15-20 GPM/sq ftCartridge: 3-5 GPM/sq ftDE: 1-2 GPM/sq ft
- You enter
- Pump GPM, filter type (sand/cartridge/DE), pool volume (gallons), max filter pressure (PSI)
- You get
- Minimum filter area (sq ft), recommended filter model, filter type comparison, max safe flow rate
How accurate is it? Larger filters better (lower pressure, longer cleaning intervals); flow rate depends on filter type/condition; dirty filters increase pressure.
These are estimates, not quotes. See How We Estimate.
Worked example
Pump delivers 50 GPM; want cartridge filter (~4 GPM/sq ft): Need 50÷4 = 12.5+ sq ft cartridge filter area.
Tap an example above the calculator to see it worked with live numbers.
Reference table
| Filter type | Flow per sq ft |
|---|---|
| Sand | 15–20 gpm |
| Cartridge | 3–5 gpm |
| DE | 1–2 gpm |
When to use it
Ensures filter is appropriately sized to handle pump output without excessive pressure and maintains water clarity.
New pool setup, pool upgrade, addressing cloudy water/low pressure, troubleshooting algae, filter replacement.