Calculate swimming pool water volume in gallons. Enter pool dimensions and shape for accurate volume and chemical dosing estimates.
Knowing your swimming pool's exact volume in gallons is essential for proper chemical dosing, heater sizing, pump selection, and water fill time estimates. Under-dosing chemicals leaves water unsafe; over-dosing wastes money and can irritate skin and eyes.
This calculator determines pool volume for rectangular, circular, and oval pools. For pools with varying depth (shallow end to deep end), it uses the average depth for an accurate calculation. Standard conversion is 7.48 gallons per cubic foot.
Whether you're filling a new pool, balancing water chemistry, or sizing a pool heater, this tool gives you the precise gallon count you need.
Precise calculations are essential for meeting regulatory requirements, passing inspections, and ensuring the long-term structural integrity and safety of the completed project. This data-driven approach helps contractors minimize rework, avoid delays caused by material shortages, and deliver projects on time and within the agreed budget.
Precise calculations are essential for meeting regulatory requirements, passing inspections, and ensuring the long-term structural integrity and safety of the completed project.
Pool chemicals, heaters, and filters are all sized based on water volume. An inaccurate estimate means improper chemical balance, undersized equipment, or wasted money. This calculator handles common pool shapes and variable depths. Consistent use of this tool across projects builds a library of reference data that improves estimating accuracy over time and reduces reliance on individual experience alone.
Average Depth = (Shallow + Deep) ÷ 2 Rectangular: Gallons = L × W × Avg Depth × 7.48 Circular: Gallons = π × r² × Avg Depth × 7.48 Oval: Gallons = π × (L/2) × (W/2) × Avg Depth × 7.48
Result: 22,052 gallons
A 32×16 ft pool with 3.5 ft shallow and 8 ft deep end: average depth = 5.75 ft. Volume = 32 × 16 × 5.75 = 2,944 ft³ × 7.48 = 22,021 gallons.
Rectangular pools are most common: L × W × Avg Depth × 7.48. Circular above-ground pools use πr² × depth × 7.48. Kidney-shaped pools are best split into a circle and rectangle, calculated separately.
Every pool chemical is dosed per gallon: chlorine, pH adjusters, algaecides, and stabilizers. A 20% volume error means 20% chemical error — enough to cause cloudy water, algae blooms, or swimmer discomfort.
Pool pumps should circulate the entire volume 1–2 times per day. Filters are sized at 1–2 GPM per square foot of filter area. Heaters are rated in BTU — larger volumes need more BTUs for the same temperature rise.
Common sizes: 12 ft round = 3,398 gal (4 ft deep). 15 ft round = 5,310 gal. 18 ft round = 7,646 gal. 24 ft round = 13,594 gal. 12×24 ft oval = 6,797 gal. Always verify with the manufacturer.
Small above-ground pools hold 3,000–7,000 gallons. Standard inground pools hold 15,000–30,000 gallons. Large residential pools can hold 30,000–50,000 gallons. Commercial pools hold 100,000+ gallons.
Measure the depth at the shallow end and the deep end. Average depth = (shallow + deep) ÷ 2. For pools with a gradual slope this is accurate. For pools with a hopper bottom, measure at 3–4 points and average.
A standard garden hose delivers about 500 gallons per hour. A 20,000-gallon pool takes about 40 hours to fill. Using two hoses cuts the time in half. Some areas require a permit for large water draws.
Chlorine dosing depends on pool volume and current levels. Typically, 1 lb of granular chlorine raises 10,000 gallons by 5–10 ppm. For maintenance, you need 1–3 ppm free chlorine, tested 2–3 times per week.
Municipal water costs $5–$15 per 1,000 gallons. A 20,000-gallon pool costs $100–$300 to fill. Water delivery by tanker truck costs $200–$600 for 6,000 gallons. Check local rates before filling.
The pump should turn over your entire pool volume in 6–8 hours. For a 20,000-gallon pool: 20,000 ÷ 8 = 2,500 gallons per hour (42 GPM). Choose a pump rated for this flow at your total dynamic head.