Pool volume calculator
Gallons in a pool from its shape and depth.
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How it's calculated
Volume is surface area times average depth, and a cubic foot of water holds 7.48 gallons. Pool builders fold the shape into one multiplier: length × width × average depth × 7.5 for a rectangle, diameter² × average depth × 5.9 for a round pool, and length × width × average depth × 6.7 for an oval. Average depth is the shallow and deep ends added together and halved. Litres are gallons times 3.785.
How do I measure average depth?
Measure the water depth at the shallow end and at the deep end and take the midpoint. If the floor has a long shallow shelf and a short deep hopper, measure the depth at several points along the length and average those instead.
Why does the pool-store number differ from mine?
Stores often quote the volume at the design water line, while you measured the actual depth, and kidney or freeform pools are estimated. A difference of 5–10% barely changes chemical doses.
What about a kidney-shaped or freeform pool?
Split it into two overlapping rectangles or ovals, calculate each and add them, or use the oval multiplier on the longest length and the average of the two widths.
Results are estimates for informational purposes only and are not financial, medical or legal advice.