Pool Filtration Size Calculator

Turn pool dimensions into dependable filtration sizing. Compare media types, pipe velocity, and pump power. Download clean summaries for bidding and on-site decisions today.

Input form
Enter pool and design parameters
Layout adapts: 3 columns large, 2 medium, 1 mobile.

Pool geometry
Use pool water surface area.
Turnover and filter sizing
Common ranges: 4–8 hours (depends on use).
Adds margin for bather load and fouling.
Override default if you have manufacturer data.
For cartridge, set to 0 if not used.
Hydraulic checks (optional)
Checks velocity at the calculated design flow.
Pump estimate is for screening only.
Reset

Formula used
  • V from geometry: Rect: V = L×W×Depth, Round: V = π×(D/2)²×Depth, Custom: V = Area×Depth
  • Convert to gallons: 1 m³ = 264.172 US gal, 1 ft³ = 7.4805 US gal
  • Required flow: Q(gpm) = V(gal) / (Turnover(hr)×60)
  • Design flow with margin: Qdesign = Q×(1 + Safety%)
  • Filter area: A(ft²) = Qdesign(gpm) / Rate(gpm/ft²)
  • Equivalent sand tank diameter: D = 2×√(A/π)
  • Backwash flow (if applicable): Qbw = A×BackwashRate
  • Pipe velocity check: v = Q/A using pipe internal area
  • Pump power screening: HP = (Q×TDH)/(3960×η)
How to use this calculator
  1. Select Calculate from dimensions or enter volume directly.
  2. Set turnover hours based on pool category and duty.
  3. Pick a filter media and adjust design rates if needed.
  4. Add safety factor to cover bather load and fouling.
  5. Optionally check pipe velocity and estimate pump power.
  6. Click Calculate, then export CSV or PDF.
For final procurement, confirm manufacturer limits, hydraulics, and codes.

Example data table
Scenario Inputs Key outputs
Residential pool 25 m × 10 m, depth 1.5 m, turnover 6 hr, sand rate 15 Flow ≈ 275.2 gpm, area ≈ 18.3 ft², sand D ≈ 57.7 in
Commercial pool Volume 75,000 gal, turnover 4 hr, D.E. rate 2.0, safety 15% Flow ≈ 359.4 gpm, area ≈ 179.7 ft², backwash depends on system
Round pool Diameter 12 m, depth 1.4 m, turnover 8 hr, cartridge rate 0.40 Flow ≈ 83.1 gpm, area ≈ 207.7 ft², cleaning by service
Example values are illustrative. Verify design inputs for your project.

Design notes for pool filtration sizing

1) Turnover time sets the required flow

Turnover time is the target period to circulate a pool’s full volume through the filtration system. The calculator uses Q = V/(T×60), then adds a safety margin. For example, a 42,000 gal pool at 6 hours needs about 116.7 gpm before margin. Shorter turnover increases flow, pipe demand, and pump power.

2) Media type guides the filtration rate

Different filters operate at different design loadings. Typical starting points are 12–20 gpm/ft² for sand or glass, 1.5–2.5 gpm/ft² for D.E., and 0.30–0.50 gpm/ft² for cartridges. Use the default presets for early sizing, then override rates with manufacturer data for final selection.

3) Filter area translates flow into equipment size

Required area is computed as A = Qdesign/Rate. Higher flow or conservative rates increase area and may require multiple vessels for redundancy. After you calculate area, choose the next larger standard model to accommodate fouling, aging media, and seasonal operating variability without exceeding the rated loading.

4) Backwash planning protects hydraulic performance

Backwash demand is estimated with Qbw = A×BackwashRate. For sand systems, a common starting range is 12–18 gpm/ft², but it varies by media and water temperature. Confirm that waste piping, drains, and makeup water can support the backwash cycle without destabilizing pool level.

5) Optional checks: pipe velocity and pump screening

The velocity check uses v = Q/A based on pipe internal area. Many designers target moderate velocities to limit noise and friction losses, especially on long runs. Pump power is screened using HP = (Q×TDH)/(3960×η); finalize selections with a pump curve, measured headloss, and required operating points.


FAQs

1) What turnover time should I choose?

Use the turnover required by local codes or project specifications. When unsure, start with 6 hours for general pools, then adjust for bather load, water features, and operating hours.

2) Why add a safety factor?

Safety margin helps cover peak bather load, filter fouling, and real-world flow reductions. A typical early-design range is 5–15%, but confirm limits with the filter manufacturer and the owner’s O&M plan.

3) Is the “sand diameter” output a real tank size?

It is an equivalent circular diameter computed from the required filter area. Use it to understand scale, then select actual commercial models by rated area, valve configuration, and allowable operating pressure.

4) When should I override filtration and backwash rates?

Override rates when the project has manufacturer submittals, special water quality goals, or unusual temperatures. Manufacturer limits and local codes should take priority over generic design ranges.

5) How does the calculator handle metric inputs?

Enter dimensions in meters or feet, or enter volume directly in m³ or gallons. The tool converts volume to gallons internally to compute gpm, then also reports m³/h and L/s.

6) Why is pump horsepower only a screening estimate?

Real pump sizing depends on system headloss, fittings, filter clean/dirty curves, elevation changes, and required operating points. Use this estimate to sanity-check, then finalize using pump curves and detailed hydraulics.

7) Can I export the results for submittals?

Yes. After calculating, use the CSV for quick spreadsheet checks and the PDF for sharing. Always attach manufacturer data and code references when submitting a final design package.

© 2026 Pool filtration sizing helper. Use engineering judgment.

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