Aquarium Volume Calculator (Litres, Gallons and Weight)
Enter your tank’s inside dimensions to get its volume and weight.
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Aquarium Volume Calculator (Litres, Gallons and Weight) by TheCalcTools
How the Aquarium Volume Calculator (Litres, Gallons and Weight) works
Volume = length × width × height for a rectangular tank, or π × radius² × height for a cylinder. 1,000 cm³ is 1 litre and 1 US gallon is 3.785 litres.
Gravel and the gap below the rim reduce the real water volume, which is what matters for medication and water-change calculations. Water weighs about 1 kg per litre, so check that your stand and floor can take the load.
The formula
Worked example
Using the default values shown in the calculator:
| Tank shape | Rectangular |
|---|---|
| Length (cm) | 90 |
| Width (cm) | 45 |
| Diameter (cm) | 50 |
| Height (cm) | 45 |
| Substrate depth (cm) | 5 |
| Gap below the rim (cm) | 3 |
- 90 × 45 × 45 cm = 182.2 litres (48.1 US gallons).
- With 5 cm of gravel and a 3 cm gap: 149.8 litres of water weighing 150 kg.
Result:
| Tank volume (litres) | 182.2 |
|---|---|
| Tank volume (US gallons) | 48.1 |
| Water volume (litres) | 149.8 |
| Water weight (kg) | 150 |
| Approximate filled weight with glass and substrate (kg) | 204 |
Frequently asked questions
How heavy is a 200-litre tank?
Roughly 250 kg once filled, with glass and gravel. Place large tanks near a load-bearing wall.
What is the 'inch per gallon' rule?
A rough beginner’s guide for small fish only. Adult size, body shape, filtration and behaviour matter far more.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.