Calculate the size of pond liner needed based on pond dimensions and depth.
Enter the pond length, width and maximum depth, then set the overlap allowance (2 ft / 0.6 m is standard). The tool works out the flat sheet of liner you need to buy, allowing for the material to drape down the sides and fold over the edges.
Liner length = pond length + (2 × max depth) + (2 × overlap). The width is worked out the same way. The depth is counted twice because the liner has to reach down and back up the opposite side.
| Input | Example |
|---|---|
| Pond length | 3 m |
| Max depth | 0.6 m |
| Overlap each side | 0.6 m |
A pond 3 m long, 0.6 m deep with 0.6 m overlap needs a liner 3 + 1.2 + 1.2 = 5.4 m long. Apply the same to the width to get the full sheet size.
Tip: always lay a protective underlay (or 25 mm of soft sand) beneath the liner to stop stones puncturing it.
Add twice the maximum depth plus twice the overlap to both the length and width of the pond.
0.75 mm (30 mil) for small ponds, 1.0 mm (40 mil) for medium, and 1.14 mm (45 mil) for large or fish ponds.
Yes – always use a protective underlay (geotextile) beneath the liner to prevent root and stone punctures.
Butyl rubber and EPDM are the most flexible and longest-lasting, making them ideal for fish ponds. PVC is cheaper but less durable and harder to repair.
Allow about 300 mm (1 ft) of liner beyond the edge all round so you can anchor it securely under stones or turf.
