Pond Liner Calculator

Work out your pond liner size

Not sure what size pond liner to buy? Our free pond liner calculator works it out for you. Enter your pond's longest, widest and deepest measurements and it tells you the liner size you need, rounded up to the nearest half metre so you're never left short.

How to measure your pond

1. Length: measure across the longest point of the pond.
2. Width: measure across the widest point.
3. Depth: measure down to the deepest point.

Always measure at the extremes, including any shelves, curves or irregular edges. You can enter your measurements in millimetres, centimetres, inches, feet or metres.

How the liner size is calculated

A pond liner has to cover the base of the pond and run up every side, so the depth is added twice to each measurement:

• Liner length = longest point + (2 × deepest point)
• Liner width = widest point + (2 × deepest point)

Each figure is then rounded up to the nearest 0.5 m. For example, a pond that is 2.3 m long, 1.2 m wide and 1 m deep needs a 4.3 m × 3.2 m liner, which rounds up to 4.5 m × 3.5 m.

The calculator gives you the liner needed to cover the pond itself. If you plan to tuck the liner under edging stones or bury it in a trench around the rim, allow a little extra on each side.

Ready to build your pond?

Once you know your size, browse our range of pond liners and underlay. Always lay underlay beneath your liner to protect it from stones and roots. Once your pond is dug, use our pond volume calculator to size your pump, filter and treatments.

Prefer to leave it to the experts? Take a look at our pond installation service, or get in touch with the Complete Koi team for advice on building your koi or wildlife pond.