Here is how to calculate pond liner size for your project:
Length: Add the maximum length, plus twice the maximum depth, plus at least one extra foot (5 feet extra with large ponds 50’+).
Width: Add the maximum width, plus twice the maximum depth, plus at least one extra foot (5 feet extra with large ponds 50’+).
The extra foot is used to compensate for error and to give you enough liner to tuck in around the edges above the maximum water level. It is a good idea to buy more than 1 extra foot, especially on large pond projects, because coming up short on liner is one of the most miserable experiences in life.
Example 1
If the maximum length of the pond is 12 feet, the maximum width is 8 feet and the maximum depth is 3 feet, here is how you would add it up:
Length: 12 + 3 + 3 + 1 = 19
Width: 8 + 3 + 3 + 1 = 15
So, you would need at least a 19 foot x 15 foot liner. We would recommend that you consider purchasing a 20 foot x 16 foot liner since it is never any fun coming up short! Also, don’t forget to use Protective Underlayment. In this example, you would want to get 32 feet of 10 foot wide underlayment.
Example 2
Same dimensions as above, but with a 2 foot rise in the center of the pond. If the maximum length of the pond is 12 feet, the maximum width is 8 feet and the maximum depth is 3 feet, with a 2 foot rise in the middle, here is how you would add it up:
Length: 12 + 3 + 2 + 2 + 3 + 1 = 23
Width: 8 + 3 + 2 + 2 + 3 + 1 = 19
As you can see, the 2 foot rise adds 2 feet going up and 2 feet going back down, which is 4 feet extra in both the length and width. So, you would need at least a 23 foot x 19 foot liner. We would recommend that you consider purchasing a 25 foot x 20 foot liner. In this example, we would also recommend a 50 foot piece of 10 foot wide underlayment.
You can view and purchase liner and underlayment directly from the following link:
Pond Liner and Protective Underlayment
Email us at info@keystonehatcheries.com for help if you are having trouble calculating how much liner you need.