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How To Calculate The Size Of Your Fish Tank Aquarium

It is important to know the actual size and volume of your fish tank aquarium for many reasons, the primary one being how many fish you are able to keep in the tank, please see our article on fish tank stocking levels for more detail on this. To calculate the size of the aquarium you must do the following calculation:

Length (cm) x Width (cm) x Height (cm) / 1000 = Size of Aquarium in Litres

For example:

120cm x 45cm x 45cm / 1000 = 243 litres

To arrive at this you might need to convert inches to cm which is 1 inch = 2.54cm

For example:

12 inches x 2.54 = 30.48cm

Lastly you may wish to convert litres to US Gallons which is 1 litre = 0.264172 US Gallons

For example:

60 US Gallons / 0.264172 = 227 litres


I hope this short guide helps you to work out what size tank you are referring to and how big your tank actually is. Don’t forget this is just the volume of tank itself and doesn’t include the volume of any external filter or sump and doesn’t take in to consideration any décor within the aquarium.