Calculate round and column fish tank volume from diameter and height.
Open live calculator →A 50 cm diameter column filled to 60 cm holds about 117.8 litres.
For a half-cylinder tank against a wall, divide the result by two.
Round aquariums follow simple cylinder geometry. Enter the internal diameter and actual water height to get litres, US gallons and UK gallons.
The live tool updates immediately and shows the result in the units commonly used by aquarium keepers around the world.
Halve the diameter for the radius—use internal glass measurements.
For a half-cylinder, divide the result by two.
Tall columns limit stocking more than the litre figure suggests.
Volume is π × radius² × water height. Measure the internal diameter, halve it for the radius, and use the actual water height rather than the full tank height.
For a half-cylinder against a wall, calculate the full cylinder and divide by two. Tall column aquariums are ordinary cylinders—just remember their small footprint limits fish choice more than the litre figure suggests.
Manufacturers quote geometric capacity to the brim. Water height below the rim, gravel and the centre column in some designs all reduce real volume, as with any tank shape.