Pond Liner Calculator
Find the liner size needed for a garden pond.
Default 1 ft
Results update as you type.
How it works
A pond liner has to reach across the bottom, up both sides, and over the edges to be secured, so it is always considerably larger than the pond's surface. This calculator finds the exact liner size you need. You enter the pond's length, width, and maximum depth, plus how much overlap you want at each edge for anchoring, and it returns the required liner length, width, and total area. The rule is simple: to each of the length and width you add twice the depth, because the liner climbs both opposing walls, and twice the overlap, because it extends past both edges. A typical overlap is about one foot, giving enough material to bury under rocks or soil to hold the liner in place and hide it. Buying a liner that is too small is a costly mistake since it cannot be stretched, so it is always better to round up. The area figure helps you compare prices, as flexible liners like EPDM rubber are usually sold by the square foot or in standard sheet sizes. Enter your pond dimensions and overlap to see the liner size to order.
Liner length = pond length + 2×depth + 2×overlap (same for width)
The liner must cover the bottom, rise up both walls, and extend past the edge to be anchored. So each dimension equals the pond's dimension plus twice the depth (for the two walls) plus twice the overlap (for the two edges). Multiplying the resulting liner length and width gives the total area.
Source:Pond installation geometry
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter pond length, pond width and pond depth.
- 2
Adjust the options
Adjust overlap each side if they apply — sensible defaults are already set.
- 3
Read your result
Liner length updates instantly as you type — no button to press.
Frequently asked questions
What size pond liner do I need?
Take your pond's length and width and add twice the depth plus twice the overlap to each. For a 10-by-6-foot pond that is 2 feet deep with 1 foot of overlap, you need a liner about 16 by 12 feet. Always round up, because a liner cannot be stretched to fit if you cut it too small.
Why add twice the depth?
The liner has to run down one wall, across the bottom, and up the opposite wall, so it covers the depth twice within each dimension. That is why you add two times the depth to both the length and the width. Forgetting this is the most common reason people buy a liner that turns out far too small.
How much overlap should I allow?
About one foot of overlap on each side is typical, giving enough liner to fold over the edge and secure under rocks, paving, or soil. Larger or informal ponds may want more, up to two feet, for a generous margin. The overlap hides the liner edge, anchors it against slipping, and lets you create a natural-looking border.
What is the best pond liner material?
EPDM rubber is the most popular choice for garden ponds because it is flexible, durable, fish-safe, and lasts decades. PVC liners are cheaper but less durable and stiffer in cold weather. For most home ponds, EPDM offers the best balance of longevity and value, and it conforms well to irregular shapes and shelves for planting.
Does pond shape affect liner size?
The calculator uses the largest length, width, and depth, which safely covers rectangular, oval, and irregular ponds that fit within that bounding box. For ponds with steep shelves or very irregular profiles, add a little extra to be safe. It is always cheaper to trim a slightly oversized liner than to discover it is too small.