Farm pond liner calculations can be confusing, but here is a simplified way to do it. One thing you may not immediately realize is that you have to factor not only for length and width, but depth. To determine pond liner size, you’ll need three numbers: The pond’s maximum length, maximum width, and the maximum depth.
To determine the length, add up the maximum length, twice the maximum depth, and add one foot extra to the calculation to make sure you have enough overlap. Thus, the calculation for a 20-foot-long pond that is five feet deep would look like this: 20+10+1=31 feet total length. Do the same calculation for the width to determine the width you’ll need for the liner.
