How many gallons in a 12×30 pool?

The 12 × 30 is the classic summer “easy set” or small frame pool. These pools are filled to roughly 90% of the wall rather than to a skimmer line, so the gap here is 3 in — and inflatable-ring pools bulge, so the real figure can be a little lower.

Small pool, small doses

At about 113 sq ft of water surface, each inch is about 70 gallons, and the whole pool is under 2,000 gallons. Pool-chemical labels written per 10,000 gallons need to be divided by about five — doses are in fluid ounces and fractions of an ounce.

• Chlorine. One ppm is about 1.9 fl oz of 12.5% liquid chlorine, or about 4 fl oz of 6% bleach. Measure with a marked cup, not by the glug.
• Tablets. A full-size 3 in tablet is far too much chlorine and stabilizer for 1,900 gallons at once; small pools use smaller tablets or liquid.
• Inflatable-ring pools (“easy set” style) slope inward, so the water surface is smaller than the base. Treat the result as an upper estimate.
• Drain or treat? A pool this size is cheap to refill, and the cartridge pumps sold with it are small; keep chlorine up daily or plan regular water changes.

A 10 ft version is a variant below. One size up: how many gallons in a 15x48 pool. Truly small paddling pools are worked out on how many gallons in a kiddie pool, and the CDC advises emptying those daily rather than chlorinating them.