Enter the shape, size and depths of the pool. The calculator works out the average depth, the volume in cubic feet and the water in US gallons and liters, which you need for chemical dosing, heaters, pumps and filling.
Pool volume formulas
Average depth = (shallow depth + deep depth) ÷ 2 Rectangle: volume = length × width × average depth Round: volume = π × (diameter ÷ 2)² × average depth Oval: volume = π × (length ÷ 2) × (width ÷ 2) × average depth Gallons = cubic feet × 7.48
Worked example: a 32 × 16 ft pool, 3.5 to 8 ft deep
- Average depth: (3.5 + 8) ÷ 2 = 5.75 ft.
- Volume: 32 × 16 × 5.75 = 2,944 cu ft.
- Gallons: 2,944 × 7.48 = 22,021 gallons (83,359 liters).
Gallons for common pool sizes
| Pool | Depth | Gallons |
|---|---|---|
| 12 ft round | 4 ft | 3,384 |
| 18 ft round | 4.5 ft | 8,565 |
| 24 ft round | 4.5 ft | 15,227 |
| 15 × 30 ft oval | 4.5 ft | 11,896 |
| 16 × 32 ft rectangle | 3.5–8 ft | 22,021 |
| 20 × 40 ft rectangle | 3.5–8 ft | 34,408 |
The U.S. Geological Survey lists 1 cubic foot as 7.48 gallons. Measure the depth to the water line, not the top of the wall, for the volume of water actually in the pool. Free-form pools can be split into rectangles and circles and added together.
Questions
How many gallons is a 24 ft round above-ground pool?
About 15,227 gallons at 4.5 ft of water.
How do I measure an irregular pool?
Split it into simple shapes, calculate each and add them.
How long will it take to fill?
Divide the gallons by your hose flow in gallons per minute. A 10 gpm hose fills 20,000 gallons in about 33 hours.
Sources
- Circular 1268: Conversion factors, U.S. Geological Survey.
Used for: 1 cubic foot = 7.48 gallons. - NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, National Institute of Standards and Technology.
Used for: Gallon to liter conversion.