How to use the pool volume calculator
- Pick the shape and measure the inside length and width, or the diameter for a round pool.
- Measure water depth at the shallow and deep ends. For a flat bottom, enter the same depth twice.
- Use the gallons figure for chemical dosing, pump sizing and fill estimates.
The formula
Volume in cubic feet = surface area × average depth. Surface area is length × width for rectangles, π × (diameter ÷ 2)² for round pools and π × (length ÷ 2) × (width ÷ 2) for ovals. Gallons = cubic feet × 7.48.
Worked example: a 16 × 32 ft pool, 3.5 to 8 ft deep
Average depth (3.5 + 8) ÷ 2 = 5.75 ft. 16 × 32 × 5.75 = 2,944 cubic feet. × 7.48 = 22,023 gallons.
Round above-ground pools
At 4 ft of water.
| Diameter | Gallons |
|---|---|
| 12 ft | 3,380 |
| 15 ft | 5,290 |
| 18 ft | 7,610 |
| 21 ft | 10,360 |
| 24 ft | 13,540 |
| 27 ft | 17,130 |
| 30 ft | 21,150 |
Rectangular in-ground pools
3.5 ft shallow end, 6 ft deep end.
| Size | Gallons |
|---|---|
| 12 × 24 ft | 10,230 |
| 14 × 28 ft | 13,930 |
| 16 × 32 ft | 18,190 |
| 18 × 36 ft | 23,030 |
| 20 × 40 ft | 28,430 |