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Calculate the water volume of your swimming pool in gallons and liters. Supports rectangular, round, oval, and kidney-shaped pools with variable or constant depth.
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Pool volume is calculated by multiplying the surface area by the average depth, then converting to gallons.
Rectangular Pool:
Length: 30 ft
Width: 15 ft
Shallow: 3 ft
Deep: 8 ft
Avg Depth = (3 + 8) / 2 = 5.5 ft
Area = 30 × 15 = 450 sq ft
Volume = 450 × 5.5 = 2,475 cu ft
Gallons = 2,475 × 7.48 = 18,513 gallons
Liters = 18,513 × 3.785 = 70,072 liters
| Shape | Area Formula | Measurements Needed |
|---|---|---|
| Rectangular | Length × Width | Length, width, depths |
| Round | π × (Diameter/2)² | Diameter, depths |
| Oval | π × (L/2) × (W/2) | Length, width, depths |
| Kidney | π × (L/2) × (W/2) × 0.85 | Length, width, depths |
Note: For irregular or freeform pools, divide the pool into sections (rectangular, round, etc.), calculate each section's volume separately, then add them together for total volume.
Fill Time Formula: Hours = Pool Gallons ÷ Flow Rate (GPM) ÷ 60
| Pool Size | Gallons | Cost* |
|---|---|---|
| Small (15×30) | 13,500 | $135 |
| Medium (20×40) | 24,000 | $240 |
| Large (25×50) | 37,500 | $375 |
| Olympic | 660,000 | $6,600 |
*Assuming $0.01 per gallon (typical municipal water)
Tip: Water delivery services often charge a flat rate ($200-400) which can be cheaper than municipal water for large pools, plus they fill faster.
For irregular or freeform pools, divide the pool into approximate shapes (rectangles, circles). Measure each section separately, calculate the volume of each, and add them together. For complex shapes, consider hiring a pool professional with measuring tools.
For standard rectangular and round pools, calculations are accurate within 2-3%. Oval and kidney shapes are approximations and may vary by 5-10%. Always round up when ordering chemicals or planning treatments to ensure adequate coverage.
For pools under 15,000 gallons, garden hoses with municipal water are economical. For larger pools (20,000+ gallons), water delivery services are faster and often comparable in cost. They can fill a 25,000-gallon pool in 1-2 hours vs. 2-3 days with a garden hose.
Pool volume is essential for proper chemical dosing (chlorine, shock, pH adjusters), calculating pump and filter sizing, determining heating costs, and planning water replacement schedules. Incorrect volume estimates lead to under or over-treatment, wasting money and potentially damaging pool surfaces.
Measure once when the pool is new. Recalculate only if you make structural changes (depth adjustment, shape modification). Pool volume doesn't change over time, though water loss from evaporation and splashing is normal (1/4" to 1/2" per day in summer).
The average inground pool in the US is 14×28 feet (392 sq ft) with a volume of 15,000-20,000 gallons. Above-ground pools average 24 feet diameter (12,000-15,000 gallons). Luxury pools often exceed 40,000 gallons.