Pool Volume Calculator

Multiply the pool's length by width by average depth to get cubic feet, then multiply by 7.48052 to convert to gallons. For a round pool, use π × radius² × average depth instead of length × width. Oval pools use the same rectangular formula multiplied by a 0.85 correction factor, since an oval holds less water than a rectangle with the same length and width.

Average depth is the mean water depth across the entire pool, which matters because most residential pools slope from a shallow end to a deep end rather than holding a constant depth. Using only the deep-end measurement overestimates your volume, while using only the shallow end underestimates it. If your pool has two depths, add the shallow and deep measurements together and divide by two to get the average depth used in the volume formula.

An oval pool's rounded ends mean it holds less water than a perfect rectangle with the same overall length and width, because the corners are curved rather than square. Pool professionals commonly apply a 0.85 factor to the rectangular volume formula to account for this lost corner space, giving a much more accurate estimate for oval and oblong above-ground pools.

A standard 16-foot by 32-foot rectangular pool with a 5-foot average depth holds about 19,000 gallons (16 × 32 × 5 × 7.48052 ≈ 19,148 gallons). Actual volume varies with the exact average depth, since pools with a shallower average depth hold less water and pools with a deeper average depth hold more.

For a round pool, use the formula π × (diameter ÷ 2)² × average depth to get cubic feet, then multiply by 7.48052 for gallons. For example, a 24-foot diameter pool with a 4.5-foot average depth holds roughly π × 12² × 4.5 × 7.48052 ≈ 15,220 gallons.

Pool volume in gallons is the basis for almost every chemical dosing calculation, since chlorine, shock, algaecide, and pH adjuster amounts are all measured per thousand gallons of water. Knowing your exact volume helps you avoid under- or over-dosing sanitizer, which keeps the water balanced and safe for swimming. Pool volume is also useful for estimating fill time, heating costs, and water bills.

To convert gallons to liters, multiply by 3.78541. A typical 19,000-gallon rectangular backyard pool holds about 71,900 liters. Liters are the standard unit for pool volume in most countries outside the US, so this conversion is useful when comparing pool sizes or product dosing instructions labeled in metric units.