Measure the length and the height of the area to be covered. Multiply these measurements to find the square footage of stone needed.
Measure the height and width of any doors or windows located in the area to be covered. Multiply the height and width of each and subtract that number from the square footage.
Measure the height of corners to be covered and add these measurements together to determine the number of corner pieces needed. Multiply that amount by .75 to find out how much area the corner pieces will cover. Subtract that number from the square footage.
Add 5 to 10 percent of the final square footage to account for cutting, breakage and waste.