Draw a basic diagram of the room or rooms you plan to carpet.
Measure the dimensions of the room and mark them down on the diagram. For each room, measure the length and width. Round up your numbers to the nearest foot.
Multiply the length by the width of each room to get the square footage for that area. Add the square footage for all the rooms together to calculate the total square footage for the carpeted area. Add 10 percent to the total in order to compensate for any seams or mistakes you make. It is always better to have extra carpet for these occasions.
Divide the square footage by 9 to calculate the square yardage of the room. As carpet is sold in square yards, you will need this number to purchase the right amount for your home.