FullCalculator

Aquarium Calculator

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Formula

Volume (gallons) = (Length x Width x Height in inches) / 231. Water weight = gallons x 8.34 lbs. Volume (liters) = gallons x 3.785. Heater: ~3 watts per gallon. Filter: 4x tank volume GPH.

Frequently Asked Questions

How do I calculate aquarium volume in gallons?
Multiply length x width x height in inches, then divide by 231 to get gallons. For example, a 36" x 18" x 16" tank is 10,368 cubic inches / 231 = approximately 44.9 gallons.
What is the 1 inch per gallon rule?
The general rule of thumb is 1 inch of adult fish per gallon of water. However, this is a simplified guideline. Larger, messier fish need more space, and tall/thin fish need different calculations.

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