Pool Volume Calculator

Multiply the surface dimensions by the average depth and a shape constant. For a rectangular pool: Length × Width × Average Depth × 7.48 = gallons. For a round pool: Diameter × Diameter × Average Depth × 5.9. Average depth is (shallow end + deep end) ÷ 2. This calculator applies the right formula automatically once you pick your pool shape.

Average depth is simply (shallow-end depth + deep-end depth) ÷ 2. A pool with a 3.5 ft shallow end and an 8 ft deep end has an average depth of 5.75 ft. If your pool is a constant depth, just enter the same value for both ends.

Every dosing calculation scales with volume — a 20% error in volume means a 20% error in every chemical you add. Getting volume right is the single most important input for accurate pH, alkalinity, calcium, and salt corrections. Measure and calculate it once rather than inheriting an estimate from a previous service provider.

Measure the longest length, the widest width, and the average depth, then apply a shape factor between 0.45 and 0.55 to account for the curved edges: Length × Width × Average Depth × 7.48 × Shape Factor. Use about 0.50 for a typical kidney shape. This calculator includes a shape-factor slider so you can dial it in.

Most residential in-ground pools hold between 15,000 and 30,000 gallons. A common 16×32 ft rectangular pool with an average depth of 5.5 ft holds roughly 21,000 gallons. Above-ground and spool (small pool) installations are often 5,000–12,000 gallons.