Volume by water depth
| Water depth | US gallons | Litres |
|---|---|---|
| 40 in of water | 6,350 gal | 24,020 L |
| 42 in of water | 6,660 gal | 25,220 L |
| 44 in of water | 6,980 gal | 26,420 L |
Formula: 18 × 18 × 3.5 ft × 5.87 = 6,662 gal.
How many gallons is an 18 ft round × 48 in above-ground pool?
An 18 ft round above-ground pool with 48 in walls holds about 6,660 US gallons (25,220 L) when filled to 42 in of water, about 6 in below the top rail. Volume depends on the water depth, not the wall height, so measure your water and check the table.
Measure your own water depth
6,662gal
About 25,220 L
Average depth 3.5 ft
Formula: diameter² × average depth × 5.87.
- Pool shapes are never perfect. Treat this as within about 10%, and check it once by adding a known amount of salt or stabilizer and testing the change.
- Use this volume: Chlorine pH Shock All-in-one
Save this test and get reminded when it is time to retest.
Pool Calc for iPhoneComing soon to the App StoreDoses for this pool
| Job | Amount |
|---|---|
| Raise chlorine 1 ppm | 8.5 fl oz of 10% liquid chlorine |
| Stabilizer 0 → 30 ppm | 1.7 lb |
| Salt 0 → 3,200 ppm | 179 lb (4.5 bags) |
Full dose tables for a pool this size: liquid chlorine for 6,000 gallons, salt and stabilizer. Or put 6,662 gallons straight into the pool chemical calculator.
Check the number once
Manufacturer capacities are usually given at a stated fill level, and liners stretch. To confirm your real volume, add a known amount of salt or stabilizer and see how much the test reading moves: the volume that explains that change is your pool.
Questions
How many gallons does an 18 ft round × 48 in pool hold?
About 6,660 gallons at 42 in of water.
How many litres is an 18 ft round × 48 in pool?
About 25,220 L at 42 in (107 cm) of water.