Pool Volume Calculator
How many gallons your pool holds, for rectangle, round, oval and kidney shapes with a shallow and deep end, plus how long it takes to fill and the salt and shock doses that go with it.
Rectangle: length × width × average depth × 7.48. Round: diameter² × average depth × 5.9. Oval: length × width × average depth × 5.9. Average depth = (shallow + deep) ÷ 2. A 16 × 32 ft pool, 3.5 to 6 ft deep, holds about 18,200 gallons; a 24 ft round above-ground pool with 4 ft of water holds about 13,600.
Gallons in common in-ground pools (4.5 ft average depth)
| Size | Gallons | Liters |
|---|---|---|
| 12 × 24 ft | 9,700 | 36,700 |
| 14 × 28 ft | 13,200 | 49,900 |
| 16 × 32 ft | 17,200 | 65,200 |
| 18 × 36 ft | 21,800 | 82,600 |
| 20 × 40 ft | 26,900 | 101,900 |
Gallons in round above-ground pools
| Pool | 48 in water depth | 54 in water depth |
|---|---|---|
| 12 ft round | 3,400 | 3,800 |
| 15 ft round | 5,300 | 6,000 |
| 18 ft round | 7,600 | 8,600 |
| 21 ft round | 10,400 | 11,700 |
| 24 ft round | 13,600 | 15,300 |
| 27 ft round | 17,200 | 19,400 |
| 30 ft round | 21,200 | 23,900 |
Frequently asked questions
How do I calculate how many gallons are in my pool?
Measure length, width and the water depth at the shallow and deep ends in feet. Average the depths, then multiply length × width × average depth × 7.48 for a rectangle, or diameter² × depth × 5.9 for a round pool.
How many gallons is a 24 ft round pool?
With 4 ft of water, about 13,600 gallons; with 4.5 ft, about 15,300 gallons.
How many gallons is a 16 × 32 pool?
About 18,200 gallons with a 3.5 ft shallow end and 6 ft deep end (4.75 ft average), or about 17,200 at a 4.5 ft average.
How long does it take to fill a pool with a garden hose?
A garden hose delivers roughly 9 gallons per minute, about 540 gallons an hour, so a 20,000 gallon pool takes around 37 hours. Time a 5 gallon bucket to measure your hose's real flow.
Why does pool volume matter?
Every chemical dose, from chlorine and shock to salt, pH and alkalinity adjusters, is calculated per gallon. Getting the volume right is the first step to balanced water.
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Volume formulas use 7.48 gallons per cubic foot; round and oval pools use π/4 × 7.48 ≈ 5.9; kidney pools use the industry approximation (A + B) × length × depth × 3.38. Real pools with steps, benches and sloped floors vary by a few percent.