🏊 Pool Volume Calculator

Calculate your pool's total volume in gallons based on its shape and dimensions.

Pool shape

Area, depth, then 7.48

Each shape gets its own area formula; all three are multiplied by average depth for cubic feet, then by 7.48 because that is how many US gallons fit in one:

rectangular  gal = length × width × avg depth × 7.48
circular     gal = π × (dia/2)² × avg depth × 7.48
oval         gal = π × (long/2) × (short/2) × avg depth × 7.48

The rectangular defaults, 30 × 15 ft at 5 ft average depth, give 2,250 cubic feet and 16,830 gallons. Switch to oval with the same numbers and it drops to 13,218, because an ellipse covers about 79 percent of the rectangle it sits inside. The result is rounded to whole gallons.

Average depth is where the error comes from

Even slope: average the two ends. A pool 3 ft at the steps and 8 ft at the drain averages 5.5 ft.
Flat shallow end then a hopper: averaging the extremes overstates it. Weight each section by how much of the floor it covers.
Freeform or kidney: use the oval setting, or take the bounding rectangle and knock off roughly 15 percent.

Half a foot of error in average depth moves a 30 × 15 ft pool by 1,683 gallons - ten percent. Since dose instructions on chemical labels are per 10,000 gallons, an optimistic depth becomes an overdose. Measure the depth rather than guessing it, and follow the label for your measured volume.

Frequently asked questions

How many gallons is a 16 x 32 ft pool?

About 19,150 gallons at a 5 ft average depth: 16 × 32 × 5 is 2,560 cubic feet, times 7.48. At a 4.5 ft average it is closer to 17,230.

Where does the 7.48 come from?

One cubic foot holds 7.4805 US gallons. If you want imperial gallons multiply the cubic feet by 6.23 instead, and for litres by 28.32.

Should I use the full depth or the water depth?

The water depth. Pools are normally filled to the middle of the skimmer opening, which leaves 4 to 6 inches of wall dry, so measuring to the coping adds gallons that are not there.