Pool volume calculator

Pool volume formulas

• Rectangle: length × width × average depth.
• Round: 3.1416 × (diameter ÷ 2)² × depth — or diameter² × depth × 0.785.
• Oval (racetrack): width × (length − width) + 3.1416 × (width ÷ 2)², times depth. This is the shape of almost every above-ground oval, and works out to the well-known 0.89 × length × width.
• Kidney: 0.45 × (width of large end + width of small end) × length × average depth.
• L-shape: split it into two rectangles and add them; the leg can have its own depth.

Feet give cubic feet: multiply by 7.48 for US gallons, 6.23 for UK gallons or 28.32 for litres. Metres give cubic metres: multiply by 1,000 for litres.

Average depth, sloped floors and hopper bottoms

For a pool that slopes evenly from 3.5 ft to 6 ft, the average depth is (3.5 + 6) ÷ 2 = 4.75 ft. Sports and hopper-bottom pools have a flat shallow end, a slope and a deep area. Choose Hopper / sports bottom and enter the length of the shallow flat and of the slope; the calculator integrates the depth along the pool. A deep hopper with sides that also slope inward holds a little less — typically 5–10% for the deep area — so treat that result as an upper bound.

Worked example

A 32 × 16 ft rectangle sloping from 3.5 to 6 ft: 32 × 16 × 4.75 = 2,432 ft³ × 7.48 = 18,193 US gallons (68,867 litres). The same pool with an 8 ft shallow flat and a 6 ft slope holds about 19,700 gallons, because more of the floor is at full depth.

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