Above-ground pool sizes and gallons chart

Round above-ground pools: gallons by wall height

gallons = 3.1416 × (diameter ÷ 2)² × water depth (ft) × 7.48

A round pool’s volume grows with the square of its size, so the steps are not even. Going from 15 ft to 18 ft adds about 44% more water; going from 24 ft to 30 ft adds about 56%. That matters for every chemical dose and for how long the hose runs.

Worked pages with the fill time, chemistry and nearby sizes: how many gallons in a 12 ft × 30 in round pool, how many gallons in a 15 ft × 48 in round pool, how many gallons in an 18 ft × 48 in round pool, how many gallons in a 21 ft round pool, how many gallons in a 24 ft round pool with a 52 in wall and how many gallons in a 27 ft round pool.

Oval above-ground pools

Most above-ground “ovals” are not true ellipses. They have two straight sides joined by half-circle ends — the shape of a running track — and that is the shape this chart uses.

oval area = 3.1416 × (W ÷ 2)² + (L − W) × W
gallons = area × water depth (ft) × 7.48

Two oval sizes have worked pages: how many gallons in a 15 × 30 oval pool and how many gallons in an 18 × 33 oval pool. Expandable-depth ovals with a dug-out deep end hold more; measure the shallow and deep water depths and use the average in the above-ground pool gallons calculator.

Small frame and easy-set pools

Pools this small are a different job from a 24-footer. A pump is usually sold with the pool, and dosing is in fractions of an ounce, so a careful measure matters more than the chart. For an inflatable kiddie pool, see how many gallons in a kiddie pool — and note the CDC says not to add chlorine or bromine to those at all; empty them daily instead.

Metric

If your pool is sold in metres, use the metric size directly: floor area in m² × water depth in m × 1,000 = litres. A 24 ft pool is 7.32 m across, which is why the same pool is often sold as 7.3 m in metric markets.

Why maker tables show different gallons

If your pool’s box or website gives another number, it is usually not wrong — it is answering a slightly different question.

• Water depth, not wall height. The chart uses wall height minus 6 in. Makers pick their own fill level. Intex lists its Ultra XTR 24 ft × 52 in pool at 12,481 gallons; on a 24 ft round floor that works out to about 44.3 in of water. Its 18 ft × 52 in pool (6,981 gallons) implies about 44 in. Both are a little under the 46 in this chart assumes.
• Percent fill. Some makers quote volume at a stated fill, such as Intex’s 16 ft × 48 in pool at “5,061 gallons (90%)”. On a 16 ft round floor that is about 40.4 in of water.
• Oval shape. A true ellipse is smaller than a straight-sided oval of the same length and width. For a 15 × 30, the ellipse is 353 sq ft against 402 sq ft for the track shape, about 12% less water. A table built on ellipses will run low for most above-ground ovals.
• Nominal size. A pool sold as “24 ft” is a nominal size; uprights, top rails and the curve of the liner at the cove mean the water surface isn’t exactly 24 ft across. A few inches either way changes the total by a few percent.
• Rounding and gallons per inch. Each inch of water in a 24 ft pool is roughly 280 gallons, so two tables that disagree by a few hundred gallons may only disagree by an inch of fill.

None of these differences matter much for chemistry — a few percent changes a chlorine dose by a few percent, and you retest anyway. They matter more for water bills and fill times.

Setting up a new pool

The pool size drives most of the shopping list. For a 24 ft round, the common sizes have worked pages:

• Base sand: how much sand for a 24 ft round pool, for an 18 ft round pool and for a 15 ft round pool.
• Liner: what size liner for a 24 ft round pool with a 52 in wall.
• Pump and filter: what size pump for a 24 ft above-ground pool; the filter sand is set by the model, e.g. how much sand an Intex SX2800 takes.
• Filling it: how long to fill a 24 ft round pool, and later gallons per inch in a 24 ft round pool for topping up.