The minimum size pond liner you need depends on the pond's dimensions, including length, width, and depth, as the liner must cover the entire surface and allow for secure edging. For a small garden pond, like one measuring 4 x 6 feet with a depth of 2 feet, a liner of at least 10 x 12 feet would be needed to ensure adequate coverage plus overlap for anchoring the liner.
A general formula to determine the minimum liner size is Length + (2 × Depth) + 2 feet by Width + (2 × Depth) + 2 feet. This calculation includes the pond's measurements plus extra liner for running up and down to accommodate depth, plus an overlap around the edges, which is crucial for securing the liner and preventing leaks.
