The maths
- Average depth = (3.5 + 6) ÷ 2 = 4.75 ft
- Volume = 20 × 10 × 4.75 = 950 cu ft
- 950 cu ft × 7.48 gal per cu ft
= 7,110 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 10 × 20 ft pool?
About 7,110 US gallons (26,901 litres) with 3.5 ft shallow end, 6 ft deep end.
How much salt does a 10 × 20 ft pool need?
About 190 lb (86 kg) to bring fresh water to 3,200 ppm, or 5 bags of 40 lb. Check your salt cell’s target first.
How much chlorine does a 10 × 20 ft pool need?
Each +1 ppm of free chlorine takes about 9 fl oz of 10% liquid chlorine. With stabilizer at 40 ppm, keep free chlorine around 4.6 ppm.