How to Calculate Swimming Pool Volume in Gallons

    Calculate the gallons in a rectangular or round pool from its dimensions and average depth, and estimate fill time.

    Knowing how many gallons your pool holds helps you dose chemicals correctly, size a pump or heater, and plan how long filling will take. The math is simple once you have the average depth.

    Rectangular pools

    Gallons = length × width × average depth (all in feet) × 7.48. There are about 7.48 US gallons in a cubic foot. For a pool with a sloped floor, average depth is the shallow end depth plus the deep end depth, divided by two.

    Worked example: a 16 × 32 foot pool, 3.5 feet at the shallow end and 6.5 feet at the deep end

    Round pools

    Gallons = π × radius² × water depth × 7.48, where the radius is half the diameter. Use the depth of the water, not the height of the wall.

    How long will it take to fill?

    Divide the gallons by the flow rate in gallons per minute, then by 60 for hours. A garden hose often delivers somewhere around 10 gallons per minute, though it varies with pressure and hose size. At 10 gallons per minute, 19,149 gallons takes about 32 hours.

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