Pond Liner Calculator
What size of liner a garden pond needs from its longest length, widest width and deepest point, with an overlap at the edges, and roughly how much water it holds.
Result
374 ft²
The overlap is the margin; liners are sold in whole sizes, so round up.
- Liner length
- 22 ft (264 in, 6.71 m)
- Liner width
- 17 ft (204 in, 5.18 m)
- Water in the pond
- 2,633 gal (352 ft³, 9,968 L)Estimate
https://calcgallery.com/landscaping/pond-liner-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use the Pond Liner Calculator
- Measure the pond at its longest and its widest, and its depth at the deepest point.
- Enter how much liner you want flat around the rim at each edge to anchor it under stone or soil.
- For the water volume, choose the outline and enter the average depth if the pond has shelves or sloping sides.
Liner size
liner length = pond length + 2 × maximum depth + 2 × overlapliner width = pond width + 2 × maximum depth + 2 × overlapThe rule measures the pond’s box, not its outline: a kidney or round pond still needs a rectangle of liner that covers its longest and widest points, and the corners are folded or trimmed. Liners are sold in fixed sizes, so choose the next size up in each direction.
Water volume
The page multiplies the surface area by the average depth, using π ÷ 4 of the box for an oval or round pond. With the maximum depth instead of the average, the figure is the most the pond could hold, which overstates a pond with sloping sides or shelves. Use it for sizing a pump or a treatment dose only with the product’s own guidance.
With your numbers
- Liner = (length + 2 × depth + 2 × overlap) × (width + 2 × depth + 2 × overlap)
- Water = surface area × average depth
Quick reference
The overlap is the margin; liners are sold in whole sizes, so round up.
| Job | Liner area |
|---|---|
| 16 × 11 ft pond, 2 ft deep | 374 ft² |
| 10 × 8 ft pond, 2 ft deep | 224 ft² |
| 20 × 15 ft pond, 3 ft deep | 644 ft² |
| 6 × 4 ft pond, 18 in deep | 99 ft² |
| 16 × 11 ft oval, 1.5 ft average | 374 ft² |
| 4 × 3 m pond, 0.8 m deep | 32.2 m² |
Common questions about the Pond Liner Calculator
- What size liner do I need for an 11 by 16 foot pond?
- At 2 feet deep, add twice the depth to each dimension for the sides, then the overlap at both edges. With no overlap that is 15 by 20 feet; with a foot of overlap at each edge it is 17 by 22 feet, 374 square feet of liner.
- Why is the depth added twice?
- Because the liner goes down one side of the pond and up the other. A cross-section of the pond at its widest shows the liner covering the width plus both walls, and the walls are each as tall as the pond is deep.
- Do plant shelves need extra liner?
- Not if you measure the length, width and depth at their largest. A shelf sits inside that outline, so the liner that reaches the deepest point already folds over it. What shelves change is the water volume, which is why the page asks for an average depth.
- How much overlap should I leave?
- Enough to anchor the edge under stone, turf or a trench. The page starts at 1 foot at each edge, the figure one pond supplier’s guide adds; your supplier may ask for more, especially for a waterfall or stream edge.