Hexagon aquarium volume calculator
Regular hexagon tanks have six equal panels. Measure the width of one panel and the height.
Hexagon volume formula
A regular hexagon with side a has an area of 3√3 ÷ 2 × a² ≈ 2.598 × a². Multiply by the height for the volume, then divide by 231 (inches → US gallons) or 1,000 (cm → liters).
Worked example
A hex tank with 12-inch panels and 24 inches tall: 2.598 × 144 = 374.1 square inches of footprint, × 24 = 8,979 cubic inches = 38.9 US gallons (147 liters). Hex tanks sold as "35 gallon" usually have panels of about 11.5 inches.
Measuring a hexagon tank
- Measure the width of a single panel along the outside, from corner to corner.
- If you can only measure across the tank: the distance between two opposite flat sides is 1.732 × the side; the distance between two opposite corners is 2 × the side.
- Elongated hexagons (two long panels and four short ones) are not regular. Treat them as a rectangle plus two triangles, or measure the water you add with a bucket of known size.
Like cylinders, tall hex tanks have little surface area for their volume. Keep stocking moderate and make sure the filter outlet breaks the surface.
FAQ
How many gallons is a hexagon tank with 12-inch sides?
At 24 inches tall it holds about 38.9 US gallons; at 20 inches, about 32.4 gallons.
How do I measure the side of a hexagon tank?
Measure one outside panel from corner to corner. Opposite corners are exactly two side lengths apart.