Liner size from the fold-down rule, pump GPH from turnover rate, and cost.
Estimates are planning aids, not a professional quote. Double-check quantities and product coverage — and any local code or permit requirements — before you buy.
| Plumbing & Heating | $329–$445 |
| Membrane & Fabric | $290–$392 |
| Pavers & Block | $211–$285 |
| Total | $829–$1,122 |
Excludes tools, delivery, tax and permit fees. Labor not included — this is a DIY materials estimate.
These are affiliate links: we may earn a commission if you buy through them, at no extra cost to you. It never changes what the calculator recommends — the shopping list comes from your dimensions, not from what pays.
About this calculator
The Pond Liner Calculator answers the question every backyard pond project starts with: how big a liner do you actually need? It's not your surface footprint — the calculator applies the fold-down rule, adding the deepest point twice to both length and width plus an overhang for anchoring the edge, so you order the right size the first time instead of coming up short mid-install.
It also sizes the pump from your pond's volume and a target turnover rate, which changes if you're stocking fish or running a waterfall, then lists underlayment, filtration, edging and a cost estimate. Toggle fish stocking and a waterfall on or off in the basic options — both change the materials list and the pump size, not just the summary text.
Step by step
A step-by-step walkthrough to go with your plan above. Follow the product instructions and any local code or permit requirements as you work.
Mark the pond's outline with a hose or marking paint, stepping back to check the shape from a few angles before you commit to a shovel. Include the marginal shelf ring in the outline, not just the deep zone.
Dig the marginal shelves first at 10–12 inches down, then step down to the deep zone at your target depth, keeping every level's edge as level as you can check with a 4 ft level laid across it.
Remove every root, sharp stone and buried debris from the excavation — this is the step that determines whether the liner survives, not the liner material itself. Lightly compact the base and shelves.
Roll the underlayment out over the entire excavation including the overhang zone at the rim, overlapping seams by at least a foot rather than butting them tight.
Center the liner over the hole and let it settle into the excavation under its own weight rather than stretching it tight corner to corner — pulling it taut now just tears it once the water's weight pulls it down further.
Start filling with a hose while smoothing and folding the liner into neat pleats at the corners and curves as the weight of the water pulls it down — do this gradually, not all at once.
Once full, trim the liner to leave your planned overhang, then anchor it with edging capstones or bury it in a shallow trench just back from the rim.
Install the skimmer, pump and any waterfall plumbing, run it for a full day to check for leaks and confirm the flow, then top off the water level before adding fish or plants.
Equip the job
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Keep planning
Garden & Yard
Answers
Not your surface area — that undersizes every liner. The real rule is the fold-down: take your pond's length and width, and to each one add the maximum depth twice (down one side and up the other) plus an overhang on both edges for anchoring the rim, typically 6–12 inches. A 12×8 ft pond with a 3 ft deep point needs roughly a 20×16 ft liner once the fold-down and overhang are added in, not a 12×8 sheet. This calculator does that math for you from your actual dimensions.
Pump size comes from your pond's volume against a target turnover rate — how many hours it should take to circulate the entire pond once. Stocked ponds need a faster turnover, generally within 2 hours, so fish waste and debris don't build up faster than the filter can process it; a still water garden with no fish can run slower, closer to once every 4–8 hours. If you're running a waterfall, the pump also has to clear that extra head, which is why turning on the waterfall toggle changes the recommended pump size even at the same pond volume.
EPDM rubber is the standard for a pond meant to last: it's flexible enough to drape over shelves and curves without stretching thin at the corners, stays supple through freeze-thaw cycles, and typically carries a 20+ year UV-stable warranty. PVC liner costs less up front and works fine for a small, shallow water-garden pond, but it stiffens in cold weather and has a shorter usable life in direct sun. If fish are staying in the pond year-round, EPDM is worth the extra cost.
Yes, unless you're lining over sand with zero roots, rocks, or sharp debris anywhere near the excavation — which almost never happens in a real yard. Underlayment is a felt or geotextile fabric that sits between the soil and the liner and absorbs the sharp edges that would otherwise work through the rubber once the pond is full and the water's weight is pressing the liner down against them. It costs a fraction of the liner itself and is far cheaper than draining a finished pond to patch a puncture.
A waterfall adds real head — the vertical lift the pump has to push water against — on top of whatever the filter box already needs. This calculator adds your waterfall height directly to that head figure before picking a pump tier, the same way a taller falls needs a stronger pump even if the pond's total volume doesn't change. As a rule of thumb, taller and wider spillways both eat into flow, so a 3 ft waterfall with a wide spillway lip needs noticeably more pump than a narrow 1 ft trickle.