Pond Liner Calculator
Enter the length, width and deepest point of the pond and how much liner to bury round the edge. You get the liner size to buy and roughly how much water the pond holds.
This is an estimate. Round up to the next size sold, and use underlay below the liner.
Worked examples
A garden pond
3 m by 2 m, 0.6 m deep, 0.5 m overlap, sloping sides
A liner of 5.2 m by 4.2 m, about 2,520 litres
The liner area is 21.84 square metres.
About Pond Liner Calculator
A pond liner calculator tells you what size of liner to buy. The liner has to go down one side, across the bottom and up the other, with a margin to tuck under the edging, so its length is the length of the pond, plus twice the depth, plus twice the overlap. The width is worked out the same way. For an irregular pond, measure the longest length and the widest width and the liner will cover it.
The tool also estimates the water volume. It multiplies the length, width and depth, then reduces the figure for the sloping sides and shelves of a typical pond, since a pond with straight sides would hold the full amount. Use the volume to choose a pump and filter. Round the liner size up to the next size sold, and add underlay below it.
How to use Pond Liner Calculator
- Enter the longest length, widest width and deepest point of the pond.
- Enter the overlap to leave round the edge.
- Choose how steep the sides are.
- Read the liner size and the volume of water.
Common uses
- Digging a wildlife pond
- Replacing an old liner
- Choosing a pond pump
- Pricing a water feature
Frequently asked questions
What size liner do I need for a 3 m by 2 m pond?
If the pond is 0.6 m deep and you leave 0.5 m overlap, the liner is 5.2 m by 4.2 m, which is 21.84 square metres. Buy the next size up.
How much overlap should I leave?
Between 30 and 50 cm on every side is normal, enough to bury the edge under paving or turf. The default is 50 cm.
How many litres is my pond?
For the same pond with sloping sides and shelves the volume is about 2,520 litres, or 554 UK gallons. Treat it as a guide for sizing a filter.
How deep should a pond be?
A wildlife pond needs a shallow edge for animals to climb out. For fish, an area at least 60 cm deep helps them to get through winter.
Do I need underlay?
It is recommended. Underlay or a layer of sand protects the liner from stones and roots and helps it last longer.