# How to Find the Volume of Basic 3-D Figures

••• cube image by drx from Fotolia.com
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Pump up the volume in your geometry equations.

Calculate the cube of the length of one side to determine the volume of a cube. Example: The volume of a cube with side length 3 is 3 x 3 x 3 = 27.

Find the volume of a rectangular prism by multiplying its length by its height, and then multiplying this product by the prism's width. Example: The volume of a 2-by-3-by-5 rectangular prism is 2 x 3 x 5 = 30.

Determine the volume of a cylinder by first multiplying the square of the radius by pi. Multiply this product by the cylinder's height. Example: The volume of a cylinder with radius 3 and height 5 is pi x 3 x 3 x 5 = 141.

Figure out the volume of a cone by first multiplying the square of the cone's radius by pi. Multiply this product by the cone's height. Divide this product by 3. Example: The volume of a cone with radius 2 and height 6 is pi x 2 x 2 x 6 x 1/3 = 25.

Multiply the cube of a sphere's radius by pi to begin finding the volume. Then multiply this product by 4/3. Example: The volume of a cube of radius 3 is pi x 3 x 3 x 3 x 4/3 = 113.

#### Tips

• Some volume problems include units. Convert length units into volume units by adding the word "cubic" before the length unit. Thus, inches become cubic inches, meters become cubic meters, and so on.