Quick chart: round pools, 52-inch wall
12 ft ≈ 3,300 gal · 15 ft ≈ 5,100 · 18 ft ≈ 7,300 · 21 ft ≈ 10,000
24 ft ≈ 13,000 · 27 ft ≈ 16,500 · 30 ft ≈ 20,400 · 33 ft ≈ 24,700
All computed at ~46 inches of actual water — the honest number for a 52-inch wall once you account for the gap below the top rail. If your water rides higher or lower, the calculator's wall-height options bracket it.
Why the wall-height detail matters
The difference between doses computed at 52 inches versus 46 inches of water is about 13% — every dose, every time, all season. It's the single most common systematic error in above-ground pool care, and it's why this page exists separately from our general pool volume calculator (which handles inground shapes and custom depths).
After you have the number
Enter it once in any calculator here and the site remembers it across all of them. The three you'll use most with an above-ground pool:chlorine dosing,stabilizer (above-grounds burn chlorine fast in full sun), and the evaporation checker when the water seems to drop too fast.