How do I calculate aquarium volume?

For a box: length × width × height (cm), divided by 1000 → litres.

How is cylinder volume calculated?

π × (diameter / 2)² × height. Width is not used for a cylinder.

Volume Calculator

Calculate the volume of a box or cylinder in cubic metres and litres. Works for tanks, pools and aquariums.

Shape: Box

Length / diameter: 100 cm

Width (box): 50 cm

Height: 50 cm

250.0 litres

Volume

Volume in litres	250.0 litres
Volume in m³	0.250 m³

ℹ️ Box: length × width × height. Cylinder: π × (diameter/2)² × height. 1000 cm³ = 1 litre.

The volume calculator works out the volume of a box or cylinder in litres and cubic metres from its dimensions. It is handy for figuring out the water in an aquarium, the capacity of a tank or the size of a pool.

How the calculator works and what it’s for▾

How the volume is calculated

A box's volume is length times width times height. A cylinder's volume is pi times the radius squared times the height, where the radius is the diameter divided by two.

When your measurements are in centimetres, the raw result is in cubic centimetres. Divide by a thousand to get litres, since 1,000 cubic centimetres equal one litre.

What you enter and what you get

First you pick the shape, a box or a cylinder. Then you enter the length or diameter, the width as well for a box, and the height in centimetres.

The result is shown in both litres and cubic metres, so the figure is immediately useful whether you are dealing with liquids or with construction.

What it is used for

Common uses include the water volume of an aquarium or swimming pool, the size of a water tank or rain barrel, and estimating the capacity of boxes and packaging for a move or for storage.

Measuring tips

Always measure the inside dimensions when you want to know how much a container actually holds, since wall thickness reduces the inner space. Use the same unit for every measurement so the result stays correct.

🔄 Reviewed June 2026