By Zencalcy Editorial TeamLast reviewed About us
A pond liner must be bigger than the pond: it goes down the walls, across the bottom and over the banks. The standard allowance is twice the maximum depth plus 2 feet of overhang in each direction, which is often 30–40% more liner than the water surface suggests.
Pond gallons, liner size and fill cost.
Liner = (L + 2 × (depth + overhang)) × (W + 2 × (depth + overhang)) Gallons = L × W × depth × 7.4805 × 0.8
The 0.8 factor accounts for sloping sides: a pond is not a full rectangular box. For an irregular shape, use the average length and width. Buy a single piece of liner — seams are where leaks start.
| Symbol | Meaning |
|---|---|
| L, W | Pond surface dimensions. |
| d | Maximum depth. |
| o | Overhang on each bank. |
Liner needed is 14 × 12 ft. The water volume is 8 × 6 × 2 × 7.4805 × 0.8 = 574 gallons.
Continue with the Pool Calculator, Round Pool Volume Calculator, Tank Volume Calculator, or the Pipe Volume Calculator — or browse more tanks, pools & flow and all construction calculators.
About 14 × 12 ft for a 2 ft depth with 1 ft of overhang on each side.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026