PondTools

Pond liner size calculator

These numbers are typed in. Trace your pond once and every calculator uses its measured volume and depths.

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Liner size you need
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How it works

Measure the hole once it is finished. Buy the next stock size up, and trim the liner after the pond is filled and has settled.

length = longest span + (2 × max depth) + (2 × overhang) + fold allowance width  = widest span  + (2 × max depth) + (2 × overhang) + fold allowance

Measure the two longest spans across the rim, at right angles to each other, and the maximum depth. The depth counts twice because the liner goes down one wall and up the other. An overhang of 12 inches on each edge is typical, and you need more for large edging or raised walls. Folds take up extra liner around curves.

Underlay is cut to the same size. Size streams and waterfalls separately, and overlap them so the water runs onto the liner below.

If you have traced the pond, this also compares the sheet size with and without the fold allowance.

Want the precise number?

Type your measurements in above for a quick estimate. For the real volume, trace your pond on a photo or satellite image and set its depths. PondTools measures the actual outline, so dosing, liner and pump sizes come out right.

Measure my pond precisely