One of the most effective materials for building walls of all types is concrete block. This dynamic material is naturally strong, durable and can be reinforced for further strength and rigidity. The consistent unit dimensions of concrete blocks make them easy for almost anyone to estimate the amount of materials needed, using only basic tools and instructions.
Measure the height and length of the wall using your tape measure, and multiply to find the total surface area in square feet.
Example: A wall measuring 20 feet long by 10 feet high has a surface area of 200 square feet.
Multiply the length of the block you are going to use by its width to find its surface area. Divide 144 (the number of inches in a square foot) by the surface area of the block to calculate the number of blocks per square foot.
Example: An 8-inch by 16-inch concrete block has a surface area of 128 square inches; 144 divided by 128 is 1.125 blocks per square foot.
Multiply the total square footage of the wall surface by the blocks per square foot to find the amount of blocks for the wall. Multiply this number by 1.06 to add a 6 percent waste margin to find the total number of blocks needed for the wall.
Example: A 200 square foot wall multiplied by 1.125 blocks per square foot needs 225 blocks. Allowing for 6 percent waste results in 239 total blocks.