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Pool Volume Calculator: How Many Gallons Is My Pool?
Find your pool's volume in gallons and liters for rectangular, round and oval pools, including pools with a shallow and deep end. Also see how long it takes to fill, what the water costs, and how much salt and shock to add.
Pool volume formulas
Find the surface area, multiply by the average depth to get cubic feet, then multiply by 7.48, the number of gallons in a cubic foot. For a pool with a sloped floor, the average depth is (shallow end + deep end) ÷ 2. For an above-ground pool, use the actual water depth, usually 6 in below the top rail.
| Shape | Gallons |
|---|---|
| Rectangle | length × width × average depth × 7.48 |
| Round | diameter × diameter × average depth × 5.87 |
| Oval | length × width × average depth × 5.87 |
Worked examples
- 16 × 32 ft in-ground pool, 3.5 to 6 ft deep: average depth 4.75 ft, so 16 × 32 × 4.75 × 7.48 = about 18,200 gallons.
- 24 ft round above-ground pool, 4.5 ft of water: 24 × 24 × 4.5 × 5.87 = about 15,200 gallons.
- 15 × 30 ft oval, 4 ft of water: 15 × 30 × 4 × 5.87 = about 10,600 gallons.
Why your pool's volume matters
Every chemical dose, from chlorine and shock to pH adjusters, is based on gallons. Getting the volume wrong by 20% means every treatment is off by 20%. It also sizes your equipment: the pump should turn the whole pool over at least once in 8 hours, so an 18,000 gallon pool needs about 38 gallons per minute of flow.
Filling and salt
- A typical garden hose delivers 6 to 12 gallons per minute, so a big pool can take a day and a half to fill. Many water utilities give a sewer credit or bulk rate for pool fills; a water truck can be quicker.
- Salt chlorine generators usually want about 3,200 ppm. Starting from fresh water, that is about 27 lb of salt per 1,000 gallons. Add less if you are topping up, and test first.
Frequently asked questions
How many gallons is a 16x32 pool?
With a 3.5 ft shallow end and 6 ft deep end, about 18,200 gallons. At an average depth of 5 ft it is about 19,150 gallons.
How many gallons is a 24 ft round above-ground pool?
About 15,200 gallons at 4.5 ft of water and 17,000 gallons at 5 ft.
How long does it take to fill a pool with a garden hose?
A typical hose delivers 6 to 12 gallons per minute. At 9 gallons per minute, a 15,000 gallon pool takes about 28 hours.