Aquarium Volume Calculator
Find how many litres or gallons your fish tank holds — and how much the water weighs.
This is the full tank capacity. Gravel, rocks, decorations and the gap below the rim usually reduce the real water volume by 10–20%. Make sure your stand and floor can carry the weight.
About this tool
Enter the length, width and height of a rectangular aquarium to get its volume in litres, US gallons and UK gallons, plus the weight of the water so you can check your stand and floor.
Frequently asked questions
Multiply length × width × height. In centimetres, divide the result by 1,000 to get litres. In inches, divide by 231 to get US gallons. A 100 × 40 × 50 cm tank holds 200 litres.
Gravel, rocks, wood and decorations take up space, and the water is usually filled a few centimetres below the rim. Expect 10–20% less water than the full capacity.
Water weighs about 1 kg per litre (8.3 lb per US gallon). A 200-litre tank holds 200 kg of water, before adding the glass, gravel and stand — so check the floor can take it.
Medication doses, water conditioner, heater size, filter flow and how many fish you can keep all depend on the volume of water.
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