Aquarium Volume Calculator
Litres, gallons, and the 250 kg your desk cannot hold.
Work out Aquarium Volume. Litres, gallons, and the 250 kg your desk cannot hold. Shows the working, not just the answer.
Water volume
180 litres
47.6 US gal · 39.6 imp gal · 225 kg set up
Internal dimensions matter, not external ones: 10 mm glass on all sides takes 2 cm off each measurement. The fill level defaults to 90% because nobody fills to the rim, and substrate and hardscape displace more still. The weight figure adds about 25% over the water alone for glass, substrate and rock. It is the number that catches people out, because a tank that two people can carry empty cannot be moved at all once wet. Surface area is deliberately shown alongside volume, because it governs oxygen exchange and often limits stocking more than volume does — a tall narrow tank holds less life than a shallow wide one of the same litres. This calculator will not give you an inch-per-gallon stocking figure, because that rule ignores that waste production scales with body mass rather than length, and it kills a great many fish.
How the Aquarium Volume Calculator works
Water volume from internal dimensions, in litres and both gallons, with the weight once it is set up. That weight is the figure nobody checks and the one that determines whether the stand is adequate.
Also known as: how many litres is my fish tank · how many gallons is my aquarium · how much does a fish tank weigh · tank volume from dimensions
Frequently asked questions
How do I calculate aquarium volume?
Internal length times width times height in centimetres, divided by 1,000, gives litres. Use internal dimensions — 10 mm glass takes 2 cm off each measurement — and fill to about 90%, since nobody fills to the rim.
How much does a fish tank weigh?
About 1.25 kg per litre once set up, allowing for glass, substrate and rock. A 200-litre tank is roughly 250 kg on a footprint smaller than a desk, which is beyond most domestic furniture and worth checking against floor joists in older buildings.
How many fish can I keep?
Not by the inch-per-gallon rule, which this calculator deliberately does not implement. Waste production scales with body mass rather than length, so ten 1-inch fish are nothing like one 10-inch fish. Stock by species requirements, filtration and tested water parameters instead.
Does tank shape matter?
Yes. Surface area governs oxygen exchange, so a shallow wide tank supports more life than a tall narrow one of the same volume. It also matters for the fish — most species use horizontal space and ignore height entirely.
What glass thickness do I need?
Pressure depends on depth, not volume. Around 6 mm suits tanks up to 30 cm deep, 8-10 mm to 45 cm and 12 mm to 60 cm. Above that, thickness and bracing need proper calculation rather than a rule of thumb.
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