Wallpaper Calculator This handy calculator will help you estimate the number of rolls of wallpaper you will need to wallpaper an interior room.   Enter the dimensions of your room: Feet Inches  Room Length  Room Width  Room Height  Height of baseboard     How Many? Width of Trim (inches) Height (inches) Width (inches)  Doors  Windows  Square feet per roll  You will need: TOTALS  Wallpaper  Single Rolls  Wallpaper  Double Rolls     Notice: This calculator is designed to help you calculate a rough estimate of the amount of wallpaper you will need for your project. You should double-check your assumptions and measurements and consult a professional at your local wallpaper retail outlet to determine your exact needs.