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Fish Tank Volume Calculator

Cylinder & Round Fish Tank Volume Calculator

Volume

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Enter your tank dimensions to see the volume.

Did we solve your problem?

Calculate the volume of a cylindrical or round aquarium. Enter the diameter and height and get the capacity in litres and gallons.

How cylinder tank volume works

A round tank is a cylinder, so its volume is pi times the radius squared times the height, where the radius is half the diameter. The calculator computes this automatically.

Shape preview

Adjust the size and height to see this tank shape and its volume.

Volume ≈ — litres

How to calculate fish tank volume

Measure the length, width and height of your tank, then multiply them together. Change the values below and the diagram and the calculation update instantly.

  1. 1

    Measure length, width and height

    60 x 30 x 30 cm

  2. 2

    Multiply them for cubic centimetres

    60 x 30 x 30 = 54,000 cm³

  3. 3

    Convert to litres and gallons

    54,000 ÷ 1000 = 54 litres (14.27 US gal)

Formulas behind the fish tank volume calculator

Prefer to calculate the aquarium size by hand? Here is the volume formula for each tank shape. Click a card to try it in the calculator.

For unusual tanks, see a triangular prism volume tool, and note that spherical aquariums (fish bowls) are not recommended for keeping fish.

Aquarium shapes

Our fish tank volume calculator supports seven popular aquarium shapes. Click any shape to load it into the calculator above.

Frequently asked questions

How do I calculate cylinder fish tank volume?
Enter the diameter and height. The formula is pi times the radius squared times the height, with the radius being half the diameter.
What is the radius of a round tank?
It is half the diameter, measured from the centre of the circular base to the edge.
How do I calculate a half or quarter cylinder?
Choose the half cylinder or quarter cylinder shape, which divide the full cylinder volume by two or four.
Are round tanks good for fish?
Tall, narrow cylinders limit swimming space and surface area, so a wider cylinder is a healthier choice.
What units can I use in this calculator?
You can switch between centimetres, millimetres, inches, feet and metres at any time. Enter all dimensions in the same unit and the result updates instantly.
Does the result include substrate and decoration?
The figure is the full internal capacity. Subtract roughly 10 to 15 percent for substrate, rocks and the gap you leave at the top to estimate the real water volume.
How accurate is this fish tank calculator?
It uses the exact geometric formula for each shape, so the result is accurate for the dimensions you enter. Measure the inside of the tank for the best accuracy.
Is this calculator free to use?
Yes. It is completely free, needs no sign-up, and works on phones, tablets and desktops.

Calculator tools

Explore our specialised fish tank volume calculators, each tailored for a specific unit, shape or region.

In Gallons In Litres Tank Size Capacity Dimensions Water Volume Tank Weight In CM In MM In Inches In Feet Metric Hexagon Corner Cylinder & Round Bow-front Triangle Octagon Pentagon Surface Area UK Australia

Related guides

Learn the core ideas behind fish tank volume before or after using the calculator.