Pool Volume Calculator
Find how many gallons your rectangular, round or oval pool holds and how long it takes to fill.
Pool volume formulas
| Shape | Gallons |
|---|---|
| Rectangular | Length × Width × Average depth × 7.48 |
| Round | Diameter² × Average depth × 5.87 |
| Oval | Length × Width × Average depth × 5.87 |
One cubic foot holds 7.48 US gallons. Average depth is (shallow + deep) ÷ 2, which is accurate for a pool with an even slope. Pools with a steep hopper or a large flat shallow area hold somewhat more or less.
A 32 × 16 ft pool that runs from 3.5 to 8 ft deep has an average depth of 5.75 ft: 32 × 16 × 5.75 × 7.48 = about 22,000 gallons. A garden hose at 10 gallons a minute would take around 37 hours to fill it.
A 24 ft round above-ground pool filled 4 ft deep holds about 13,500 gallons.
Why the volume matters
Chemical labels, pump and filter sizes and heater ratings are all stated per gallon. A pump should turn over the full volume in about 6 to 8 hours. Follow the dosing instructions on the product label for your pool size, and test the water before adding chemicals.
Frequently asked questions
How many gallons is a 24 ft round pool?
About 13,500 gallons at 4 ft of water and about 16,900 gallons at 5 ft.
How do I measure average depth?
Add the shallow and deep end depths and divide by two. Measure to the water line, not the top of the wall.
How long does it take to fill a pool with a hose?
A typical garden hose delivers 9–12 gallons per minute, so a 20,000 gallon pool takes about 28–37 hours.
Last reviewed October 2026. Results are estimates; check important decisions with a qualified professional.