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Aquarium Volume Calculator (Litres and Gallons)
Work out how much water a fish tank holds: rectangular, cylinder, hexagon, or quarter-circle corner tanks in cm or inches, at the water level you keep, in litres, US gallons, and UK gallons, with the weight of the water.
Aquarium Volume Calculator (Litres and Gallons): The base area, length × width for a rectangle, π r² for a cylinder, or the hexagon or quarter-circle area, is multiplied by the water depth. A 60 × 30 × 40 cm tank holds 72 L when full and 64.8 L filled to 90%, which is 17.1 US gallons and weighs about 65 kg. Runs 100% locally in your browser with zero server file uploads.
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Volume is the base area times the water depth, measured inside the glass: a 60 × 30 × 40 cm tank holds 72 L when full and about 65 L filled to 90%, before gravel, rock, and decorations take some space. Water weighs 1 kg per litre, so check that the stand and the floor can carry the full weight. Medicine and water-conditioner doses go by the water volume, not the tank's nominal size.
Gallons
A US gallon is 3.785 litres and a UK gallon 4.546 litres, so the same tank holds about 20% more US gallons than UK ones; tanks sold in the United States are usually labelled in US gallons. Convert any amount with litres to gallons.
Stocking
The old rule of one inch of fish per gallon is a rough guide at best: active and large fish need far more room, and filtration matters more than volume.
How to use it
- Choose the tank shape and units.
- Enter the inside dimensions and the water level.
- Read the volume and the weight.
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Frequently asked questions
Should I measure inside or outside the glass?
Inside, if you can: thick glass can take several litres off a large tank's outside measurements.
Why does medicine dosing matter?
Treatments and water conditioners are dosed by the water volume; gravel, rock, and decorations reduce it, so dose for the real amount of water.
How heavy is a full aquarium?
Water weighs 1 kg per litre, plus glass, gravel, and rock, often 10 to 20% more; make sure the stand and floor can take it.
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