Measure the dimensions of the structure you wish to build. You will have to know the length and height, in inches, of each wall you want to construct.
Calculate the number of 16-inch cinder blocks required to build your wall. A standard cinder block is 8 inches deep, 16 inches long and 8 inches high. For example, to calculate the number of blocks needed for a 320-inch-long wall that will be 80 inches high, divide the length by 16, yielding 20 blocks, and the height by 8, giving 10 blocks. Multiply the two numbers together and you will get the total number required to build that wall; 20 times 10 equals 200 blocks needed for that wall.
Calculate the amount of sand and mortar required to construct the wall. You will need 600 pounds of sand and 2.5 bags of mortar mix for each lot of 100 cinder blocks that you intend to use. In this case you are using 200 cinder blocks, so double the total of each amount, totaling 1,200 pounds of sand and five bags of mortar.