Volume Is Area × Depth × 7.48

Every pool volume calculation is the same shape: surface area times average depth times 7.48 — the exact number of US gallons in a cubic foot of water. What changes with shape is the surface-area formula: rectangles use length × width, round pools use πr², and ovals use the ellipse approximation. Irregular freeform pools average out to about 60% of a rectangle's volume.

Why the Number Matters

Pool chemicals are dosed per 10,000 gallons, so a 20% volume error means a 20% dosing error. Sanitizer, shock, and algaecide all scale with true volume — over-dosing wastes money and can irritate swimmers; under-dosing fails to keep the water safe. The average depth (shallow + deep ÷ 2) is the most common input mistake.

Filling Costs Real Money

At municipal rates, filling an average residential pool runs $50–150. Water trucks cost more per gallon but are needed where fill times are extreme or utility rates are tiered. Know the volume before you open the tap — the fill-cost line here uses your local rate per 1,000 gallons to turn gallons into dollars.