Aquarium Volume Calculator

Volume Formulas

• Rectangular: V = L x W x H (then divide by 231 for US gallons from cubic inches)
• Cylindrical: V = pi x r² x H
• Bow-Front: Modeled as a rectangular base with a parabolic bow segment added. V_bow = (2/3) x bow_depth x L x H
• Hexagonal: V = (3 x sqrt(3) / 2) x side² x H (area of regular hexagon times height)

Glass Thickness Deduction

Interior dimensions are smaller than the outer frame by twice the glass thickness on each axis. The calculator deducts glass thickness from both ends of each relevant dimension before computing volume.

Stocking Capacity

The classical guideline is 1 inch of adult fish per gallon. This calculator adjusts for fish size category because large fish produce more waste per inch of body length and need more swimming room:

• Small fish: 1 inch per gallon (densely schooling species)
• Community fish: 1 inch per gallon (tetras, rasboras, small barbs)
• Medium fish: 0.5 inch per gallon (more waste, more territory)
• Large fish: 0.25 inch per gallon
• Aggressive / territorial: 0.15 inch per gallon (territory needs dominate)

These are conservative guidelines. Always research the specific needs of your fish species, including water parameters, swimming zone, and social requirements.

Filter Size

Filters are rated in gallons per hour (GPH) or liters per hour (LPH). A good filter should turn over the tank volume 4-6 times per hour. This calculator recommends a filter rated for 5x turnover, which works well for most community setups. Heavily stocked or predator tanks may need 8-10x turnover.

Weight of Water

1 US gallon of water weighs approximately 8.34 lbs (3.78 kg). The total weight of a filled tank also includes the glass, substrate, rocks, and equipment, which can easily add 50-100% more. Make sure your stand and floor can support the load.