Knowing your tanks volume is vital when using treatments or working out stocking values.

It is a good idea to write down your volume and keep it somewhere safe (e.g. on the inside of your aquarium cabinet door)

You can take off roughly 10% of your volume to account for decor (rocks, gravel etc.) and space above the water line.

Choose your tank shape from the calculators below, enter your tanks measurements in centimetres (cm) and click 'calculate' to work out your tanks volume.

Fishtank Volume
Rectangular / Square tanks

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Width (cm)
Length (cm)
Height (cm)

Your fish tank volume is:
Litres
Imperial Gallons
US Gallons

Fishtank Volume
Cylindrical tanks

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Diameter (cm)
Height (cm)

Your fish tank volume is:
Litres
Imperial Gallons
US Gallons

Fishtank Volume
Corner tanks

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Distance A (cm)
Distance B (cm)
Height (cm)

Your fish tank volume is:
Litres
Imperial Gallons
US Gallons

Fishtank Volume
Hexagon tanks

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Distance A (cm)
Distance B (cm)
Height (cm)

Your fish tank volume is:
Litres
Imperial Gallons
US Gallons

Fishtank Volume
Octagon tanks

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Distance A (cm)
Distance B (cm)
Height (cm)

Your fish tank volume is:
Litres
Imperial Gallons
US Gallons

Fishtank Volume
Spherical tanks

Enter the circumference of your tank below to work out the radius. Radius is also half the diameter, or height, of your sphere.
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Enter your radius below:
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Radius (R)

Your fish tank volume is:
Litres
Imperial Gallons
US Gallons