How to Calculate Round Aquarium Volume

Choosing the right size fish tank is important because some fish and aquatic plants often require a specific amount of space in which to thrive. Larger or more active aquatic animals will require more swimming space. Round tanks can take up less space while holding the same amount of water as rectangular tanks. The volume of a round or spherical fish tank can be determined by taking one measurement and using three equations.

Things You'll Need

  • Measuring tape marked in centimeters
  • Calculator
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Instructions

    • 1

      Measure the circumference of the spherical fish tank using a measuring tape marked in centimeters (cm). The circumference is measured around the equator of the aquarium, which is its widest part. For example, the circumference could be 100 cm.

    • 2

      Determine the radius of the fish tank by using this equation: radius = C/2pi, where C is the circumference that was measured in centimeters and pi is approximately equal to 3.14. In the example, 100/(2 x 3.14) = 15.9. The radius of your tank is 15.9 cm.

    • 3

      Calculate the volume of the spherical aquarium with this equation: volume = (4/3)pi(radius^3). In the example, 4/3 x 3.14 x 15.9^3 = 16829. The volume of your tank is 16,829 cubic centimeters.

    • 4

      Divide your tank volume in cubic centimeters by 1000. In the example, 16829/1000 = 16.829. The liquid volume of your tank is about 17 liters.