4 calculators
Polygon Aquarium Volume Calculators
Polygon tanks are built from flat panels arranged around a centre. Regular polygons have equal sides and need only one panel width plus the height. The flat back hexagon is the important exception: six sides, but a long back panel and short sides for wall placement.
Hexagon
Six-sided polygon tank
Flat-Back Hexagon
Wall-mounted hex tank
Octagon
Eight-sided polygon tank
Pentagon
Five-sided polygon tank
How polygon tanks are measured
Measure a single panel between its two seams for regular polygons. Do not use the width across the tank unless you convert it: face-to-face width is 1.732 × side on a hexagon and 2.414 × side on an octagon.
Formula differences
Floor area is a constant times side squared: 2.598 for a hexagon, 4.828 for an octagon and 1.720 for a pentagon. The flat back hexagon is a rectangle minus two triangular corners.
Common mistakes
- Entering the tank width as the side length.
- Using the regular hexagon formula on a flat back hexagon.
- Assuming all panels are equal on a stretched polygon.