How to Determine the Gallons an Aquarium Will Hold

Pet fish are enjoyable and don't require as much care as other types of animals. Many sizes of aquariums are available and are often measured by how many gallons they hold. If you want to fill an aquarium with water but don't know its capacity, a couple measurements gives you an accurate idea of how many gallons of water you will be able to fit into your aquarium.

Things You'll Need

  • Paper
  • Pen
  • Tape measure
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Instructions

    • 1

      Measure the aquarium length from left to right. Write down the length in inches.

    • 2

      Measure the aquarium from top to bottom. Write down the measurement in inches.

    • 3

      Measure the width of the aquarium. Write down the number of inches wide the aquarium is from front to back.

    • 4

      Multiply the three measurements. This will tell you how many cubic inches your aquarium is. Multiply the three numbers together. For example, if your aquarium is 24 inches by 16 inches by 18 inches, your equation would be 24 x 16 x 18 = 6,912 cubic inches.

    • 5

      Multiply the cubic inches of your aquarium by 0.00433. Continuing the example, 6,912 cubic inches by 0.00433 equates to 29.92. This is the number of gallons your aquarium will hold.