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Pool Volume Calculator
Calculate pool volume in gallons and liters, plus chemical estimates for startup
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Pool Volume Calculator
How to Calculate Pool Volume
Pool volume depends on shape, dimensions, and depth. Most pools have a shallow end and deep end, so we use the average depth in calculations.
Pool Volume Formulas
Rectangle: Length × Width × Avg Depth × 7.481 = Gallons
Circle: π × (Diameter/2)² × Avg Depth × 7.481 = Gallons
Oval: π × (L/2) × (W/2) × Avg Depth × 7.481 = Gallons
Kidney: 0.85 × Length × Width × Avg Depth × 7.481 = Gallons
Rectangle: Length × Width × Avg Depth × 7.481 = Gallons
Circle: π × (Diameter/2)² × Avg Depth × 7.481 = Gallons
Oval: π × (L/2) × (W/2) × Avg Depth × 7.481 = Gallons
Kidney: 0.85 × Length × Width × Avg Depth × 7.481 = Gallons
Pool Size Reference Chart
| Pool Size | Avg Depth | Volume (Gallons) |
|---|---|---|
| 12×24 ft Rectangle | 5.5 ft | ~14,900 |
| 16×32 ft Rectangle | 5.5 ft | ~26,500 |
| 18×36 ft Rectangle | 5.5 ft | ~33,500 |
| 20 ft Circle | 5 ft | ~11,780 |
| 15×30 ft Oval | 5 ft | ~13,250 |
Pool Chemical Startup Checklist
- Shock chlorine: 3 lbs per 10,000 gallons to reach ~10 ppm
- Alkalinity increaser: 1.5 lbs per 10,000 gallons to reach 80–120 ppm
- pH adjustment: raise to 7.4–7.6 (use pH up or pH down as needed)
- Calcium hardness: 175–225 ppm (calcium chloride if low)
- Stabilizer/CYA: 30–50 ppm for outdoor pools
- Filter sand: 200 lbs per 10,000 gallons
? Frequently Asked Questions
How many gallons is a typical pool?
A standard 12×24 ft rectangular pool with a 4–8 ft average depth holds approximately 15,000–20,000 gallons. An 18×36 ft pool holds around 30,000–40,000 gallons. Use our calculator for precise estimates.
How much chlorine do I need to start up a pool?
For initial chlorination (shock), add 3 lbs of granular chlorine per 10,000 gallons. For a 20,000 gallon pool, you need about 6 lbs. Shock the pool to 10 ppm, then maintain at 1–3 ppm for regular use.
How long does it take to fill a pool?
At 1,000 gallons per hour (typical garden hose), a 20,000 gallon pool takes 20 hours. City water at 5 gallons per minute (300 gph) would take 67 hours. Some municipalities require water delivery for pools over 10,000 gallons.
How do I calculate pool volume for an oval pool?
Use the formula: π × (Length/2) × (Width/2) × Average Depth for the cubic feet, then multiply by 7.481 for gallons. Our calculator handles oval, rectangle, circle, and kidney shapes automatically.
How much filter sand do I need?
Sand filters typically need about 200 lbs of filter sand per 10,000 gallons of pool water. A 20,000 gallon pool requires approximately 400 lbs of #20 silica sand. Replace filter sand every 3–5 years.
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💡 Pro Tips
Always add 10% extra to material estimates to account for waste, cuts, and mistakes.