The keeper’s toolkit
Know your tank.
Estimate the water volume of a rectangular aquarium.
Estimated usable volume
litres
- US gallons
- 12.8
- Imperial gallons
- 10.7
- Before displacement allowance
- 54.0 L
How it works
For dimensions in centimetres: length × width × water height ÷ 1,000 gives litres. Inches are converted using 2.54 cm per inch. One US liquid gallon is 3.785411784 litres; one imperial gallon is 4.54609 litres.
Use internal dimensions and the actual water height for a better estimate. The allowance reduces the result by the percentage you choose. Curved, bow-fronted and irregular tanks need a different calculation.
Volume alone does not determine stocking. Species needs, swimming space, filtration and water quality also matter.