Pool Volume Formula
The Formula
| Symbol | Description | Unit |
|---|---|---|
L | Pool length in feet | ft |
W | Pool width in feet | ft |
D | Average depth in feet ((shallow end + deep end) ÷ 2) | ft |
7.48 | Gallons per cubic foot (conversion constant) | gal/ft³ |
Worked Example
A rectangular pool is 16 ft wide, 32 ft long, with a 3 ft shallow end and a 6 ft deep end.
- Average depth = (3 + 6) ÷ 2 = 4.5 ft
- Volume = 32 × 16 × 4.5 × 7.48
- Volume = 32 × 16 = 512 ft²
- 512 × 4.5 = 2,304 ft³
- 2,304 × 7.48 = 17,234 gallons
This pool holds approximately 17,200 gallons.
How This Formula Works
Every pool chemical dose is calculated per volume of water. An inaccurate volume means every chemical calculation is wrong by the same percentage. The formula multiplies the three dimensions of the pool (length, width, depth) to get cubic feet, then converts cubic feet to gallons using the constant 7.48.
- For pools with a gradual slope from shallow to deep, average depth = (shallow end depth + deep end depth) ÷ 2.
- For oval pools, multiply the rectangular formula result by 0.89 to account for the rounded corners.
- For circular pools, use the formula: π × radius² × depth × 7.48.
- For L-shaped or irregular pools, divide the pool into sections, calculate each section's volume, and add them together.
Limitations & Notes
The rectangular formula assumes a flat bottom or uniform slope. It does not account for pool features that reduce water volume such as benches, steps, ledges, attached spas, or irregular wall profiles. For pools with complex shapes, calculate each distinct section separately and sum the results.
Last reviewed: 2026-06-01