Plywood, particle board and other types of sheeting usually are available in a standard size of 4 feet by 8 feet. The thickness of the sheet is variable, and you must determine whether you need heavy 3/4-inch sheeting that can hold a lot of weight, or lighter-weight sheeting for non-structural purposes. The price can vary based on the thickness of the plywood you need to buy and your location, so check with your local lumber yard.
Things You'll Need
Measure both the length and the width of the space where you are installing the plywood, whether it is a floor, roof wall or other surface. If you are covering several spaces, measure each separately. Measure in feet; round up the nearest foot.
Calculate the area by multiplying the length by the width. If you measured multiple spaces, calculate the areas separately and add the totals. For example, if you are putting plywood sheeting on a floor that measures 11 feet by 19 feet, the area you need to cover is 209 square feet.
Multiply the areas from Step 2 by 1.1, then round up to the nearest foot. This adds 10 percent for waste. In the example from Step 2, you get 229.9, which rounds up to 230 square feet.
Divide your plywood need from Step 3 by 32, which is the square footage of your 4- by 8-foot sheet. In the example, you get 7.2 as the number of sheets you need. Unless you can buy a partial sheet, you need to buy eight sheets.
Multiply the number of sheets by the price of a sheet of plywood in the proper thickness.