How to Calculate the Volume of Water in an Aquarium

Calculating the water volume in your aquarium is necessary when deciding what type of aquatic creatures to fill it with. Most fish need a certain amount of space, so the volume of the tank will limit the type of fish that can live in it. The volume also has an effect on tank population, as the tank must have enough water to handle waste and exchange carbon dioxide and oxygen.

Things You'll Need

  • Ruler
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Instructions

    • 1

      Measure the width of the aquarium in inches. The width is the measurement across the front. Be sure to measure from the inside of the glass; otherwise, the thickness of the tank walls will be added to the measurement and skew the calculation.

    • 2

      Measure the depth of the aquarium in inches. This is the measurement from front to back.

    • 3

      Measure the height of the aquarium in inches. This is the measurement from top to bottom. If the water is not filled to the top, just measure to the top of the water.

    • 4

      Multiply the width times the depth times the height.

    • 5

      Divide the value from step 4 by 231; 231 cubic inches equals one gallon. The resulting value is the number of gallons in the tank.