Pool Volume Calculator: Swimming Pool Gallons & Liters
Use this pool volume calculator to determine exact water capacity in US gallons and liters for accurate chemical dosing, salt chlorination, pump sizing, and pool heater selection. Handles sloped depths across all major pool geometries.
Pool capacity: 22,980 US Gallons (86,989 Liters). Recommended pump sizing: ≥ 47.90 GPM flow rate for an 8-hour turnover cycle.
| Pool Shape Profile | Rectangular (32' × 16') |
|---|---|
| Average Water Depth | 6 ft (3.5' shallow to 8.5' deep) |
| Total Cubic Volume | 3,072 cu ft (87.0 m³) |
| US Liquid Gallons | 22,980 gallons |
| Metric Liters | 86,989 liters |
| 8-Hour Turnover Flow Rate | 47.9 GPM minimum |
| Initial Salt Requirement (3,200 ppm) | 620 lbs pool salt (~16 × 40-lb bags) |
How to Measure for Pool Volume Calculator
- Measure pool interior length and width at the water surface line (not the coping rim).
- For sloped bottom pools, record the shallow-end depth and deep-end depth to calculate the true average water depth: `(Shallow + Deep) / 2`.
- For kidney-shaped pools, measure length along the longest axis, plus two separate width measurements across the wide lobes.
- Always measure water depth from the pool floor to the mid-skimmer operating water line, which is typically 4 to 6 inches below the top coping stone.
How the Calculation Works
Water volume is calculated from geometric cubic volume and multiplied by the fluid conversion constant: 1 cubic foot of water = 7.48052 US gallons (or 28.3168 liters). For a rectangular pool: `Gallons = Length × Width × Average Depth × 7.48`. For circular pools: `Gallons = π × Radius² × Average Depth × 7.48`. For oval pools: `Gallons = π × (Length / 2) × (Width / 2) × Average Depth × 7.48`. For kidney pools, the standard hydraulic multiplier is `0.45 × (Width A + Width B) × Length × Avg Depth × 7.48`.
- Average depth = (3.5 + 8.5) / 2 = 6.0 ft. Surface area = 16 × 32 = 512 sq ft. Cubic volume = 512 × 6.0 = 3,072 cubic feet. Water volume in gallons = 3,072 cu ft × 7.48052 = 22,980 gallons. Metric volume = 22,980 × 3.78541 = 86,990 liters.
Pool Volume Calculator Reference & Specifications
| Standard Pool Size & Shape | Average Depth | Volume (US Gallons) | Volume (Liters) | Typical Turnover Pump Size |
|---|---|---|---|---|
| 12 ft Round Above-Ground | 4.0 ft | 3,380 gal | 12,800 L | 1/2 HP Pump |
| 18 ft Round Above-Ground | 4.0 ft | 7,600 gal | 28,800 L | 3/4 HP Pump |
| 24 ft Round Above-Ground | 4.5 ft | 15,200 gal | 57,500 L | 1.0 HP Pump |
| 12 × 24 ft Rectangular In-Ground | 5.0 ft | 10,770 gal | 40,800 L | 3/4 HP Variable Speed |
| 16 × 32 ft Rectangular In-Ground | 5.5 ft | 21,060 gal | 79,700 L | 1.5 HP Variable Speed |
| 18 × 36 ft Rectangular In-Ground | 6.0 ft | 29,080 gal | 110,100 L | 1.5 – 2.0 HP Variable Speed |
| 20 × 40 ft Rectangular In-Ground | 6.0 ft | 35,900 gal | 135,900 L | 2.0 HP Variable Speed |
| 16 × 32 ft Kidney In-Ground | 5.5 ft | 18,950 gal | 71,700 L | 1.5 HP Variable Speed |
Frequently Asked Questions About Pool Volume Calculator
Why is knowing exact pool volume so critical for water chemistry?
All pool chemical dosages (chlorine shock, stabilizer/CYA, muriatic acid, and calcium hardness) are formulated per 10,000 gallons. Underestimating volume leads to chronic under-chlorination and algae blooms, while overestimating volume causes skin irritation, scaling, and chemical waste.
How do I calculate the average depth of my pool?
Add the shallow end depth to the deep end depth and divide by 2. For example, if your shallow end is 3 ft and your deep end is 8 ft: (3 + 8) ÷ 2 = 5.5 ft average depth. If your pool has a large extended shallow lounge area before a sharp drop, take depth measurements at three intervals (shallow, middle, deep) and divide by 3.
How many gallons of water are in one cubic foot?
One cubic foot of water equals exactly 7.48052 US liquid gallons (and weighs approximately 62.4 pounds). To find gallons from cubic feet, multiply your total cubic volume by 7.48.
How many hours should my pool pump run each day?
Most residential health guidelines recommend turning over the entire volume of pool water at least once every 24 hours. For a 20,000-gallon pool operating an energy-efficient variable speed pump at 42 gallons per minute (GPM), one turnover takes approximately 8 hours (20,000 ÷ 42 ÷ 60 = 7.9 hours).
How much pool salt do I need for a saltwater chlorine generator?
Most saltwater chlorine generators require a salinity level of approximately 3,200 parts per million (PPM). For a brand-new freshwater fill, you need approximately 26 to 28 pounds of high-purity pool salt for every 1,000 gallons of water (approx 520 lbs of salt for a 20,000-gallon pool).