About Aquarium Volume Calculator
Aquarium Volume Calculator converts tank dimensions into gross capacity and can estimate the actual amount of water after accounting for fill level and displacement from substrate, decor, and equipment.
Inputs are processed locally in your browser and are not sent to Navorika.
How the calculation works
Rectangular aquarium
Volume = length × width × height. When dimensions are in centimetres, dividing cubic centimetres by 1,000 gives litres.
Cylindrical aquarium
Volume = π × radius² × height.
Actual water estimate
Filled volume is adjusted by the selected fill percentage and then reduced by the estimated displacement percentage.
How to use this calculator
- 1Choose rectangular or cylindrical tank shape.
- 2Choose centimetres or inches and enter the aquarium dimensions.
- 3Set the approximate water fill level.
- 4Optionally estimate the percentage displaced by substrate, rocks, wood, or equipment.
- 5Review estimated litres, US gallons, UK gallons, and cubic feet.
Understanding the result
Gross capacity represents the mathematical internal volume based on the entered dimensions.
Actual water volume is usually lower because aquariums are not filled to the rim and objects inside the tank occupy space.
Important limitations
- The calculation assumes simple rectangular or cylindrical geometry.
- Curved-front, bow-front, corner, irregular, or partitioned aquariums require more detailed measurements.
- Glass or acrylic thickness is not automatically deducted.
- Displacement percentage is only an estimate and depends on the actual contents of the aquarium.
Frequently asked questions
How do I calculate aquarium litres?
For a rectangular tank measured in centimetres, multiply length × width × height and divide the result by 1,000.
Why is actual water volume lower than tank capacity?
The tank is normally not filled completely and substrate, decorations, equipment, rocks, and other objects displace water.
Does the calculator support gallons?
Yes. It displays both US gallons and UK or Imperial gallons.
Can I calculate a cylindrical aquarium?
Yes. Choose Cylindrical and enter its diameter and height.