Pool Volume Calculator (Gallons)
Know your pool's volume before you buy chemicals or a pump. Get gallons and liters for rectangular, round or oval pools with shallow and deep ends, plus salt for a saltwater system and how long a hose takes to fill it.
Pool volume
How to calculate pool volume
- Choose the shape and enter the length and width (or diameter for round pools).
- Enter the shallow and deep end depths; for a constant depth, enter the same number twice.
- For salt systems, enter the target and current salt levels from your chlorinator's manual and test strips.
Pool volume formulas
A cubic foot holds about 7.48 US gallons. For a rectangle, volume is length × width × average depth × 7.48. For a round pool it is π × radius² × average depth × 7.48, and for an oval π × (length ÷ 2) × (width ÷ 2) × average depth × 7.48. Average depth is the mean of the shallow and deep ends, which is a good approximation for a gradual slope.
Salt needed is simple physics: water weighs about 8.34 pounds per gallon, so raising salt by 1,000 ppm in 10,000 gallons takes about 83 pounds. Most salt chlorine generators run at 2,700–3,400 ppm; check your model's manual and add salt gradually, retesting after it dissolves.
Knowing the exact volume makes every chemical dose more accurate. Chemical product labels give amounts per 10,000 gallons, so divide your volume by 10,000 and multiply.
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Frequently asked questions
How many gallons are in my pool?
Multiply length × width × average depth × 7.48 for a rectangular pool. A 32 × 16 ft pool averaging 5.75 ft holds about 22,000 gallons.
How much salt does a pool need?
About 8.34 lb per 1,000 gallons for every 1,000 ppm. A new 20,000-gallon pool at 3,200 ppm needs about 530 lb.
How long does it take to fill a pool with a hose?
A typical garden hose delivers about 6–10 gallons per minute, so a 20,000-gallon pool takes roughly 35–55 hours.
Does the shape of the deep end matter?
Hopper-shaped deep ends hold a bit less than a straight slope. For best accuracy, measure sections separately.