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Aquarium Volume Calculator
Find the gallons and litres of a fish tank.
Aquarium volume
—
US gallons.
| Litres | — |
|---|---|
| Fish capacity | — |
| Dimensions | — |
| — |
Show our math
Enter your figures above to see the step-by-step working.
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How the Aquarium Volume Calculator Works
A rectangular tank’s volume is length × width × height, and since there are 231 cubic inches in a US gallon, dividing by 231 gives the gallons. A 24×12×16-inch tank holds just under 20 gallons. The figure is the full glass volume; actual water is a bit less once you add gravel, rocks and leave headroom.
A common stocking rule of thumb is one inch of adult fish per gallon, though it varies widely by species, filtration and tank shape.
gallons = length × width × height ÷ 231
Frequently Asked Questions
How many gallons is my fish tank?
Multiply length × width × height in inches and divide by 231. A 24×12×16 tank is about 20 gallons.
How many fish can my tank hold?
A rough guide is one inch of adult fish per gallon, but species, filtration and shape matter a lot.
Is the water volume the same as tank volume?
A little less — gravel, decorations and headroom reduce the actual water by roughly 10%.
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