Pool shape volume multipliers (derivation)

The quick multipliers turn length × width × average depth (feet) straight into gallons. They come from 7.48 gallons per cubic foot and the area factor of each shape.

ShapeMultiplierDerivation
Rectangular / square7.5L × W × avg depth × 7.48 (a box)
Round5.9π/4 × 7.48 ≈ 5.87 (circle area factor)
Oval5.9π/4 × 7.48 ≈ 5.87 (ellipse area factor)

gallons ≈ multiplier × length × width × average depth (all in feet).