Most potted plants are in pots shaped as hemispheres or cylinders. Determining the volume of a hemisphere allows a grower to calculate the amount of soil the pot will hold. The basic calculation for volume of a hemisphere is two-thirds times pi times the radius cubed, while the formula for cylinder volume is pi times the radius squared times the height.
Volume of a Hemisphere
Measure the radius of the pot. The radius of a hemisphere is from the bottom of the pot to the top of the pot. For example, a pot has a radius of 2 feet.
Cube the radius of the pot. In the example, 2 cubed is 2 times 2 times 2, which equals 8.
Multiply the radius cubed by pi. Pi equals approximately 3.14. In the example, 8 times 3.14 equals 25.12.
Multiply the number calculated in Step 3 by two-thirds. In the example, 2/3 times 25.12 equals approximately 16.75 cubic feet.
Volume of a Cylinder
Measure across the base of the pot. For example, the pot's base is 6 inches.
Measure the height of the pot from top to bottom. In this example, the pot's height is 11 inches.
Divide the base in half to calculate the radius of the pot. In the example, 6 inches divided by 2 equals a radius of 3 inches.
Square the radius by multiplying the number by itself. In the example, 3 inches times 3 inches equals 9 square inches.
Multiply the radius squared by the height and pi to calculate volume of the pot. Estimate pi as 3.14. In the example, 9 times 11 times 3.14 equals a volume of 310.86 cubic inches.
About this Author
Carter McBride started writing in 2007 with CMBA's IP section. He has written for Bureau of National Affairs, Inc and eHow. He received a CALI Award for The Actual Impact of MasterCard's Initial Public Offering in 2008. McBride is a New York state attorney with a Juris Doctor from Case Western Reserve University, and a Master of Science in accounting from the University of Connecticut.