Gallons in a 18 ft round pool, by water depth
The surface area is 254 ft². The fill time is for a garden hose delivering 9 gallons per minute.
| Water depth | Gallons | Liters | Hose fill time |
|---|---|---|---|
| 3 ft | 5,711 | 21,617 | 10.6 hrs |
| 3.5 ft | 6,662 | 25,220 | 12.3 hrs |
| 4 ft | 7,614 | 28,823 | 14.1 hrs |
| 4.5 ft | 8,566 | 32,426 | 15.9 hrs |
| 5 ft | 9,518 | 36,029 | 17.6 hrs |
By wall height
Above-ground pools are normally filled about 6 inches below the top of the wall:
| Wall height | Typical water depth | Gallons |
|---|---|---|
| 48 in wall | 42 in | 6,662 |
| 52 in wall | 46 in | 7,297 |
| 54 in wall | 48 in | 7,614 |
Why you need the number
Pool chemical doses are given per number of gallons, and the pump and filter are sized to circulate the pool's volume. Always measure the water depth in your own pool and follow the label on any product you add.
Want to change anything else? The calculator above is the full Pool Volume Calculator: edit any number and the results update instantly.
Tools & materials for this project
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Frequently asked questions
How many gallons in a 18 foot round pool?
About 7,614 gallons at a flat 4 ft water depth, 8,566 at 4½ ft, and 6,662 at 3½ ft. The depth you measure to the water level is what counts.
How many gallons in a 18 ft pool with 52 inch walls?
Pools with 52 inch walls are usually filled to about 46 inches, which holds roughly 7,297 gallons for a 18 ft round pool. Your actual water depth may differ.
How long does it take to fill a 18 foot round pool with a hose?
At 9 gallons per minute, filling to 4 ft takes about 14.1 hours (0.6 days). Time your own hose: fill a 5 gallon bucket and divide.
Related sizes and guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.