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Free tool · Metric m / L
Pool & Spa Filter Size Calculator
Get the right sand, cartridge or DE filter for your pool or spa in seconds. Enter your dimensions, or skip ahead if you already know your water volume.
1. Pool Size
2. Filter Requirements
Water Volume
— Litres
Required Flow Rate
— LPM
≈ — GPM
Recommended Filter
—
Based on your water volume and selected turnover rate. For best results, choose a filter at or above this size.
Shop Compatible Filters →
Accurate Volumes
Industry-standard formulas
Real-World Sizing
Flow-rate based recommendations
Easy to Use
Metric metres and litres
How the Calculator Works
01
Choose Type & Shape
Select Pool or Spa, then pick the shape that matches your setup.
02
Enter Size or Litres
Provide dimensions in metres or skip ahead with your known water volume.
03
Get Filter Sizing
See a recommended sand, cartridge or DE filter size based on flow rate.
Frequently Asked Questions
How is my pool or spa volume calculated?
We multiply the surface area of your shape by the average depth, then convert cubic metres to litres. One cubic metre equals 1,000 litres.
What does turnovers per day mean?
It is the number of times your filter circulates the full water volume each day. Pools typically use 1–2 turnovers per day, while spas usually need more due to higher bather load.
Which filter type is best for me?
Sand filters are low-maintenance, cartridge filters offer finer filtration and save water, and DE filters provide very fine filtration but need more upkeep.
Can I oversize my filter?
Yes. Choosing a filter rated above the calculated flow is generally safe and can reduce strain on the system. If you are between sizes, choose the next size up.