Calculating Liner Size

Flexible pool lining materials are flexible in more ways than one because you can build a pool any size or any shape you want. There are several materials available which can be expected to give good, long-term service.

The size of the liner required for the pond, regardless of the shape, size or position of the marginal shelves, is arrived at by the following formula:

  • Length –  The length of the liner is the overall length of the pond plus twice the maximum depth. If your depth is in inches, make sure to transfer it into feet before calculating. 
    • ( Length + (2 * Depth))
  • Width – The width of the liner is the overall width of the pond plus twice the maximum depth. If your depth is in inches, make sure to transfer it into feet before calculating.  
    • (Width + (2 * Depth))

For Example – A pond with overall dimensions of 12 feet by 7 feet and a depth of 18 inches (1.5 feet) will require a liner of 15 feet by 10 feet.

If the formula produces a liner size in which both length and width are in odd numbers of feet, then a slight alteration to the design is necessary. The length of the pond may be altered by 1 foot or the depth by 6 inches.

It will be noticed that no allowance is made for overlap at the edge of the pond. This is because the elasticity of the material and the inward slope of the walls of the pond create a surplus for an overlap, which is sufficient without making special allowances.

The freedom of design offered by liners may tempt you to an excess of irregular shapes, full or narrow necks, promontories, bays and inlets. These are perfectly possible, but wasteful since the liner can be supplied only as a square or rectangular sheet. It is obvious that the more complicated the pond shape becomes, the more waste will occur. Simple shapes with sweeping curves are best; they are more economical, as well as more impressive, than narrow-wasted designs.