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Aquarium Size Calculator - Tank Volume & Fish Capacity
Free aquarium size calculator. Calculate tank volume in gallons and liters. Determine how many fish your aquarium can hold.
Aquarium Size Calculator
Calculate tank volume and capacity
Tank Specs
Enter your values to see results
and click the "Calculate" button
Aquarium Size Calculator
Calculate your aquarium's volume and fish capacity. Remember to account for substrate, decorations, and equipment which reduce actual water volume.
Volume Formula
Gallons = (L × W × H) / 231 (inches) | Liters = L × W × H / 1000 (cm)
Actual water volume is ~10-15% less due to substrate and décor. Water weighs 8.34 lbs/gallon.
Frequently Asked Questions
How many fish can I have?
Old rule: 1 inch of fish per gallon. Better: research each species. Active fish need more space. Consider adult size, not purchase size.
Is my stand strong enough?
Water weighs 8.34 lbs/gallon + tank + substrate. A 55-gallon tank = 500+ lbs. Most furniture can't handle this. Use proper aquarium stand.
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