Measure the perimeter of the area to be constructed. For our purposes, we'll use a patio 20 feet long by 20 feet wide.
Multiply the length and width of the patio to get the area. In the example, this works out to length (20 feet) times the width (20 feet), which equals 400 square feet.
Measure the length and width of your preferred paver stone. For this example, the stone will be 4 inches long and 4 inches wide.
Multiply the length and width of the paver stone to learn its area. In the example, the length (4 inches) times the width (4 inches) is equal to 16 square inches.
Convert the area of the patio from square feet to square inches by multiplying the area by 144. When you do so, you will find that 400 square feet times 12 is equal to 57,600 square inches.
Divide the area of the patio in square inches (57,600) by the number of square inches in a stone (16). When you divide 57,600 by 16, you arrive at 3,600. This is the amount of stones you need to exactly pave the area.
Add 15 percent to the total of stones needed. When you multiple 300 by .15, you arrive at 540, which is the number of extra stones needed. For the example, the total number of stones needed is 4,140.