Design liners for oval, round, or freeform ponds. Add overlaps, shelves, and waterfall extensions today. Download results, plan cuts, and reduce material waste significantly.
| Shape | Footprint | Depth | Slope (H:1V) | Overlap | Waste | Seams | Recommended liner | Final liner area |
|---|---|---|---|---|---|---|---|---|
| Rectangle | 3.0 × 2.0 m | 0.8 m | 1.0 | 0.3 m | 10% | 5% | 5.38 × 4.38 m | 25.71 m² |
| Round | 3.0 m diameter | 0.9 m | 1.5 | 0.3 m | 12% | 0% | 6.72 m diameter | 39.79 m² |
| Oval | 4.0 × 2.5 m | 0.75 m | 1.0 | 0.25 m | 8% | 4% | 6.07 × 4.57 m | 25.57 m² |
A liner must cover the pond footprint, the sidewalls, and an edge allowance for anchoring. This calculator adds side coverage using a slope-based distance and then adds an overlap on every edge. For a 0.8 m deep pond at a 1.0 (H:1V) slope, side coverage is about 1.13 m per side, before overlap.
Steeper sides increase the liner sheet quickly. The side distance uses depth × √(1 + slope²). At the same 0.8 m depth, a slope of 2.0 increases side coverage to about 1.79 m per side. This extra area can change the purchase roll size.
Overlap supports anchoring in a trench, under coping stones, or behind edging. Many pond builds use 0.25–0.45 m per edge depending on finish. Waste allowance (often 8–15%) accounts for folds and trimming. Seam allowance (typically 0–10%) helps when joining panels or planning future repairs.
Underlay is sized from the same footprint plus waste, so you can order protection material consistently. The shelf option adds a ledge width and splits depth into upper and lower runs, which is useful for plant shelves at 0.20–0.35 m depth. This helps you plan both liner and edging for multi-level designs.
Enter liner and underlay prices per area unit to estimate a budget. The output provides both recommended sheet dimensions and final liner area after allowances. For ordering, round up to the next roll size and keep a margin for rocks, corners, and settlement. Export CSV or PDF for supplier quotes and site planning.
If your pond has curves, start with freeform using maximum length and width. It gives a safe sheet estimate. Refine later by measuring multiple chords and keeping the largest values for ordering.
Common overlap ranges are 0.25 to 0.45 units per edge, depending on edging style and trench depth. If you will hide liner under stones or coping, choose the upper end of the range.
Use 8–12% for simple shapes and gentle slopes. Use 12–15% when you expect heavy folding around shelves, tight corners, or rock edging. Higher waste reduces the risk of running short.
Add seam allowance when you expect to join panels, patch around penetrations, or plan future repairs. If you are buying one continuous sheet and have a simple shape, seam allowance can be 0%.
No. Geometry comes from footprint, depth, slope, and overlap. Material affects durability, flexibility, and installation approach. Use the material selector for documentation and exports, not for changing dimensions.
Underlay typically follows the pond footprint and side coverage, then adds waste for trimming. This calculator estimates underlay from the same extras plus waste, helping you order consistent protection coverage.
The footprint is only the base. The liner must also climb sidewalls based on slope and depth, then extend beyond the edge for anchoring. Those additions often exceed the base footprint area.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.