How this calculator works
Surface area × average depth gives the volume in cubic feet. Each cubic foot holds about 7.48 US gallons. For pools with a sloped floor, the average of shallow and deep depths is used.
Rectangle area = Length × Width
Round area = π × (Diameter ÷ 2)²
Oval area = π ÷ 4 × Length × Width
Gallons = Area × Average depth × 7.48
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Pool shape | Rectangle |
| Length | 32 ft |
| Width | 16 ft |
| Shallow end depth | 3.5 ft |
| Deep end depth | 6 ft |
| Result | Value |
|---|---|
| Pool volume | 18,193 gallons |
| Pool volume | 68,866 liters |
| Average depth | 4.75 ft |
| Surface area | 512 sq ft |
Step by step:
- Average depth = (3.5 + 6) ÷ 2 = 4.75 ft
- Surface area = 512 sq ft
- Gallons = 512 × 4.75 × 7.48 = 18,193
Above-ground round pool volumes
Water depth 4 ft.
| Diameter | Pool volume |
|---|---|
| 12 ft | 3,384 gallons |
| 15 ft | 5,288 gallons |
| 18 ft | 7,614 gallons |
| 21 ft | 10,364 gallons |
| 24 ft | 13,536 gallons |
| 27 ft | 17,132 gallons |
| 30 ft | 21,151 gallons |
Common mistakes to avoid
- Measuring to the top of the wall instead of the water line.
Frequently asked questions
How many gallons is a 24 ft round above-ground pool?
At 4 ft of water about 13,500 gallons; at 4.5 ft about 15,200 gallons.