To use our wallpaper calculator, please type in the length of your room, the width of your room and your ceiling height. You then need to fill in the number of doors and windows in the room. Our calculator will tell you the number of single rolls of wallpaper that you will need to wallpaper the room, and give you the number of spools of border that you will need. Note: This calculator is meant to estimate the amount of wallcoverings that you will need for your project. Interior Place will not be responsible for overage or shortages based on your measurements.