I had a hexagonal aquarium as a kid and wanted to use it now, 20 years later, as a Quarantine Tank.  But ummm, I didn’t know how many gallons it was.  So after searching thru like 20 google pages, I realized… it should be easier to calculate it.  So I want to simply explain how:



You need 2 Formulas:

where B is the area of the Triangle and H is the height of the triangular prism (so basically the height of the aquarium)


FORMULA 2: B=(bh)/2
where b is the base or “width” of the triangle (or 1 side of the hexagon) and h is the height of the triangle (not the triangular prism; only the triangle; so basically, the “radius” of the aquarium)

Plug in your numbers. My tank is 10″ high. One hexagon side is 5″ wide. Radius of my Tank is 6″.


B=(5*6)/2 | so B = 15


V= 150 cubic inches

NOW MULTIPLY THAT BY 6 and you get 900 cubic inches.

Visit www.google.com and type “900 cubic inches” and a converter automatically comes up, and select gallons and your answer is:

3.9 Gallons