Size of the Goal
Not all basketball goals are the same height and weight. Some are built lower for children, but others prefer goals 10 feet off the ground. Long J-bolts hold the base of the basketball goal in the concrete foundation. The taller your basketball pole, the deeper into the ground you will need to dig the hole. A deeper hole will require more cement.
Depth of the Hole
How deep you dig the hole for your basketball goal will depend on your region. The bottom of the concrete needs to be lower than the depth where the ground freezes in your area. Usually holes for supporting basketball posts will be between 36 and 48 inches deep.
Calculating the Volume
You will need to determine the volume of the hole with some calculations. Measure the depth and width of the hole. Divide each number by 12 to find the width and depth in feet. Divide the width in half to determine the radius. Multiply the radius by itself then multiply the result by pi, approximated at 3.14. Take this number and multiply it by the depth of the hole to find the volume in cubic feet.
Determining Cement Amount
Concrete is purchased by the cubic yard. Divide the volume of the hole in cubic feet by 25 to find the volume in cubic yards and to factor in an 8 percent overrun for mistakes. If you want to find the exact volume without the extra, divide the volume in cubic feet by 27.