Pool Ratio

18 ft round pool: how many gallons?

A 18 ft round pool with 4 ft of water holds about 7,610 US gallons (28,823 litres). Here is what that means for salt and chemicals.

Last updated · Checked against published product doses · How we calculate

Volume
7,610 gal
28,823 litres · 4 ft of water
Salt to 3,200 ppm (new salt pool)203 lb · 6 × 40 lb bags
10% liquid chlorine per +1 ppm10 fl oz
Stabilizer 0 → 40 ppm2.5 lb
Baking soda per +10 ppm alkalinity1.1 lb
Calcium chloride (77%) per +10 ppm15 oz

Open the chemical calculator for this pool →

The maths

  1. Area = π × 9² = 254.5 sq ft
  2. Volume = 254.5 × 4 = 1,018 cu ft
  3. 1,018 cu ft × 7.48 gal per cu ft

= 7,610 US gallons

Real pools vary: water levels sit a few inches below the wall top, floors slope and corners are rounded. If your pool’s depth differs, adjust it in the volume calculator.

Frequently asked questions

How many gallons is a 18 ft round pool?

About 7,610 US gallons (28,823 litres) with 4 ft of water.

How much salt does a 18 ft round pool need?

About 203 lb (92 kg) to bring fresh water to 3,200 ppm, or 6 bags of 40 lb. Check your salt cell’s target first.

How much chlorine does a 18 ft round pool need?

Each +1 ppm of free chlorine takes about 10 fl oz of 10% liquid chlorine. With stabilizer at 40 ppm, keep free chlorine around 4.6 ppm.

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