Boneyard Tools

Pond Liner Calculator: What Size Liner Do I Need

Work out the liner a garden pond needs. Enter the pond length, width and maximum depth, set the edge overlap, and get the liner size, area and water volume.

How to size a pond liner

  1. Enter the pond length and width at the water surface.
  2. Enter the maximum depth and the flat overlap for each edge.
  3. Read off the liner length, width, area and estimated water volume.

Examples

10 by 6 ft pond, 2 ft deep, 2 ft overlap

Length 10, width 6, depth 2, overlap 2
18 by 14 ft liner, 252 sq ft

Frequently asked questions

What size pond liner do I need?

Add twice the maximum depth and twice the edge overlap to each of the pond length and width. For a 10 by 6 ft pond that is 2 ft deep with a 2 ft overlap, the liner is 18 by 14 ft.

Why add twice the depth to the liner size?

The liner has to drop down one side to the bottom and rise up the other side, so each dimension gains the depth twice. The overlap is added on both edges as well to anchor the liner under rocks or soil.

How much overlap should I leave?

Around 1 to 2 ft per edge is typical. That gives enough flat liner to weigh down and hide, and to allow for settling. The calculator uses 2 ft by default.

How is the water volume estimated?

It multiplies the surface area by an average depth of about 60% of the maximum, then converts to gallons. Real ponds with sloped sides hold less than the full depth, so this is an approximation.

Should I round up to a stock liner size?

Yes. Liners come in set sizes, so round the calculated length and width up to the next size sold. A little extra is easy to trim and protects against measuring error.

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