How much pond liner do I need?

Calculating the amount of pond liner you’ll need is really easy!

All you need to know is the widest point, the longest point and the deepest point.

To calculate the width we use the calculation:

Width = widest point + deepest point + deepest point.

To calculate the length we use the calculation:

Length = longest point + deepest point + deepest point.

Calculating pond liner needed example

For example let’s say we want to create a pond that has a surface area of 3m wide and 5m long and the maximum depth is 50cm.

First let’s calculate the width of the liner needed.

3m (width) + ( 0.5m (depth) x 2) = 4m.

Next we calculate the length needed.

5m (length) + (0.5m (depth) x 2) = 6m.

So for this particular pond we will need to purchase a pond liner that is 4m wide and 6m long.

That calculation gives you the exact amount of liner needed with no flexibility.

I much prefer to oversize the liner a would add a full extra metre to the length and width.

So for this particular example i would purchase a liner that is 5m wide and 7m long.

Creating multiple pools and waterfalls

Sometimes you might want to create a series of pools or waterfalls that cascade down and embankment or pre existing slope.

To line the entire area just isn’t cost effective.

A better way is to use a seperate piece of liner for each and every pond or pool.

This helps minimise waste and saves you money.

The video below shows how to overlap the liners so they wont leak.

To use this method you’ll need to have an elevation change of at least 20cm between to pools.

If that isn’t possible you’ll want to seam the liner. Below is another video showing how to seam two pond liners together.

What type of liner should i use?

The pond liner is an incredibly important part of any pond build. Trying to save money on a pond liner may cost much, much more in the long run!

In my opinion EPDM pond liner is the best choice for any DIY pond builder.

If you would like to read about some of the other options that are available check out my article on selecting the right pond liner.

Protect the liner

The liner is often the most expensive part of the pond build. Do consider adding some or all of these suggestions to protect the liner:

  • Remove all rocks and roots from the hole.
  • Excavate more than required if ground is very rocky or there is lots of roots in the area. Then use  a layer of sand to cushion the liner.
  • Use rocks and gravel within the pond. These will help protect the liner from sunlight but more so any animals that fall in and scratch up the liner trying to escape.
  • Use a geotextile underlay. These are really cheap and like sand provide a nice soft cushion for the liner. You’ll need the same amount as the pond liner you ordered. This doesn’t need to be the exact width and length. Just make sure the square metre amount is the same.
  • Provide gentle sloping beach areas or shallow spots for animals and kids to enter the pond. If they are entering and exiting in deeper areas it can potentially stretch the liner or bunch it up. This can possibly cause tears or potential leak spots.
  • For more formal looking ponds add a framing of timber or rock on top to protect the liner. Still provide a shallow area where animals can enter and exit. This could be as simple as a beautiful piece of drift wood partly in and partly out of the water.


From time to time suppliers and distributors reach out to me and offer special discounts on pond related products including pond liner.

Im more than happy to pass these discounts on to the readers of ozponds. If you’d like to received these offers sign up to our mailing list so they can be sent through.


G'day, I'm Kev. My pond and water garden started with simple aquariums. I have created many ponds and water gardens around our home: Fish ponds, Aquaponic systems, grey-water wetlands and bog filters. My favourite topic is water filtration.

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