Pool Volume Calculator
Calculate how many gallons of water your swimming pool holds for rectangle, round and oval pools, plus water weight and pump turnover time.
How many gallons are in a pool?
Multiply length × width × average depth in feet, then multiply by 7.48 to get gallons. A 12 × 24 ft rectangular pool with a 5 ft average depth holds about 10,772 gallons. For a round pool use 3.1416 × radius² × depth × 7.48.
Formula: rectangle area = length × width round area = π × (diameter ÷ 2)² oval area = π ÷ 4 × length × width gallons = area × (shallow + deep) ÷ 2 × 7.4805 turnover hours = gallons ÷ (pump GPM × 60)
| Pool size | Average depth | Gallons |
|---|---|---|
| 10 × 20 ft rectangle | 4.5 ft | 6,732 |
| 12 × 24 ft rectangle | 5 ft | 10,772 |
| 16 × 32 ft rectangle | 5 ft | 19,150 |
| 18 ft round | 4 ft | 7,614 |
| 24 ft round | 4.5 ft | 15,228 |
| 15 × 30 ft oval | 4 ft | 10,575 |
How to calculate pool volume
- Choose the shape of your pool. For a rectangle, enter the length and width of the water surface. For a round pool, enter the diameter measured straight across the middle. For an oval, enter the longest length and the widest width. Kidney and freeform pools can be estimated as an oval or split into two simpler shapes and added together.
- Enter the depth at the shallow end and at the deep end, measured to the water line rather than the top of the wall. The calculator averages the two depths, which works well for pools with a steady slope. If your pool has a constant depth, such as most above ground pools, enter the same number in both boxes.
- The surface area is multiplied by the average depth to get cubic feet, and each cubic foot holds about 7.48 US gallons. If you add the flow rate of your pump in gallons per minute, the calculator also shows how long one full turnover takes, which is the time needed to push the entire pool through the filter once.
Formula
rectangle area
Where:
- 7.4805
- = US gallons in one cubic foot
- GPM
- = Pump flow rate in gallons per minute
Worked example
A 32 by 16 foot rectangular pool that runs from 3 feet to 8 feet deep has an average depth of 5.5 feet. The surface area is 512 square feet, so the volume is 2,816 cubic feet.
That is 2,816 × 7.4805 = about 21,065 gallons, or roughly 79,740 liters. With a 50 GPM pump, one turnover takes about 7 hours.
Using your pool volume for water care
Every chemical label lists a dose per 10,000 gallons, so divide your pool volume by 10,000 and multiply by the dose. Test the water with strips or a kit before adding anything, and add chemicals slowly while the pump is running so they spread evenly. Keep chlorine between 1 and 3 parts per million and pH between 7.2 and 7.8 for comfortable swimming.
Write the volume of your pool somewhere easy to find, like inside the pump house or on your phone. It also helps when buying a new pump, heater or salt system, because these are sized by gallons. Measure again if you change the water level or add steps, as both reduce the true volume.
Frequently asked questions
Find the surface area of the water, multiply by the average depth in feet to get cubic feet, then multiply by 7.48. Round pools use π times the radius squared for the area.