How Do I Calculate Pond Volume? | Water Garden Ltd - FAQ

How Do I Calculate Pond Volume?

For square and rectangular ponds and lakes, please use our simple volume calculator below.  For circular ponds, calculate as a square, then reduce the pond volume stated by 20% (1/5th).  Most pond filter choices are based around Litres (not gallons) so make a note of your volume in Litres for future use.  Below the calculator is a link to our Pond Filters Wizard which will automatically select the right filter for your pond, once you know the water volume.

Volume Calculator


View our Pond Filters Wizard here.


Calculating pond volume manually.

The simplest way to calculate your pond volume would be to work out the surface area in m2 (square metres) and then multiply it by the depth to produce m3 (cubic metres). The volume in m3 then needs to be multiplied by 1000 to give a measurement in litres.


Rectangular pond: 3m L x 1.5m W x 0.75m D

3m x 1.5m = 4.5m2

4.5m2 x 0.75m = 3.375m3

3.375m3 x 1000 = 3375 Litres

Circular ponds are calculated differently.  You will need to firstly work out the surface area of the pond by multiplying the radius by itself and then by Pi ( πr² ). The surface area is then multiplied by the pond depth to give the volume in m3. This value should be multiplied by 1000 to give a value in litres.


Circular pond: 3m diameter x 0.6m depth

3m / 2 = 1.5m (Radius)

1.5 x 1.5 = 2.25

2.25 x π (Pi is roughly 3.14) = 7.065m²

7.065 x 0.6 = 4.239m3

4.239 x 1000 = 4239 Litres

Complex ponds such as kidney shapes will need to be closely estimated. In the case of a kidney shaped pond you would form a rectangle around all outer perimeters and estimate a percentage of what is dry land. Calculate the pond as a rectangle and the remove this percentage from the total surface area before multiplying by the depth.

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