Pond Liner Calculator
Calculate the exact liner size for your pond or water feature. Enter length, width, and maximum depth to get the liner dimensions including overlap for anchoring, plus underlay fabric and cost.
Pond Liner Material Comparison
EPDM (ethylene propylene diene monomer) is the most popular pond liner material. It is flexible, UV-resistant, fish-safe, and lasts 20 to 30 years. The 45-mil thickness handles most residential ponds. PVC liners cost less but become brittle in cold climates and have a shorter lifespan. HDPE (high-density polyethylene) liners are the strongest option, used for large ponds and commercial applications, but they are stiff and difficult to work with in complex shapes. For small ponds under 100 square feet, preformed rigid liners are an easy alternative.
Sizing Tips for Irregular Ponds
For freeform and kidney-shaped ponds, measure the longest length and widest width, then add 10 to 15 percent to each dimension to account for curves and contours. The liner will fold and pleat along curves, requiring extra material. Mark your pond outline with a garden hose before digging to finalize the shape. Create shelves at 12-inch depth intervals around the perimeter for placing plants at different water depths. The overlap beyond the pond edge should be buried under soil and stone to anchor the liner and create a clean finished look.
Frequently Asked Questions
What is the pond liner formula?
Liner length = pond length + (2 x max depth) + (2 x overlap). Liner width = pond width + (2 x max depth) + (2 x overlap). Use 2 feet of overlap on each side.
What thickness of pond liner should I use?
Use 45-mil EPDM for most garden ponds. Larger or deeper ponds benefit from 60-mil EPDM. PVC liners (20-mil) are cheaper but last only 10 to 15 years versus 20 to 30 years for EPDM.
Do I need underlay under a pond liner?
Yes. Geotextile underlay protects the liner from rocks, roots, and burrowing animals. It is essential for long liner life and costs only a fraction of the liner itself.