Wallpaper Calculator
Plan your home & garden project with our free wallpaper calculator. Get precise measurements, material lists, and budgets.
Formula
Rolls = ceil(Total Strips / Strips per Roll); Strips = Perimeter (in) / Roll Width
Calculate the room perimeter and divide by the wallpaper roll width to find total strips needed. Determine strips per roll by dividing roll length by the effective strip height (wall height adjusted for pattern repeat). Divide total strips by strips per roll and round up to get the number of rolls.
Worked Examples
Example 1: Standard Bedroom
Problem: A 15 ft x 12 ft room with 8 ft ceilings using standard 20.5-inch x 33-ft rolls with no pattern repeat.
Solution: Perimeter = 2(15 + 12) = 54 ft = 648 inches\nStrips needed = ceil(648 / 20.5) = 32 strips\nStrips per roll = floor(33 / 8) = 4\nRolls = ceil(32 / 4) = 8 single rolls\nDouble rolls = 4
Result: 8 single rolls (4 double rolls)
Example 2: Dining Room with Pattern
Problem: A 14 ft x 14 ft room, 9 ft ceilings, 20.5-inch x 33-ft rolls with a 12-inch pattern repeat.
Solution: Perimeter = 56 ft = 672 inches\nStrips = ceil(672 / 20.5) = 33\nStrip height with repeat = ceil(9 / 1) x 1 = 9 ft\nStrips per roll = floor(33 / 9) = 3\nRolls = ceil(33 / 3) = 11 single rolls
Result: 11 single rolls (6 double rolls)
Frequently Asked Questions
How many rolls of wallpaper do I need for a room?
Calculate your room perimeter by adding all wall lengths, then determine how many vertical strips fit around the room by dividing the perimeter (in inches) by the wallpaper roll width. Next, figure out how many strips you can cut from each roll by dividing the roll length by your wall height. Finally, divide total strips needed by strips per roll and round up. Always buy one extra roll for mistakes, future repairs, and pattern matching waste.
What is the difference between single and double rolls of wallpaper?
Wallpaper is priced per single roll but almost always packaged and sold in double rolls. A single roll of American wallpaper is typically 20.5 inches wide by 33 feet long, yielding about 56 square feet of coverage. A double roll is the same width but 66 feet long, providing about 112 square feet. European wallpaper rolls are usually 21 inches wide by 33 feet. Always confirm roll dimensions before ordering.
What is pattern repeat and how does it affect wallpaper quantity?
Pattern repeat is the vertical distance between identical points in the wallpaper design. When hanging patterned wallpaper, each strip must be aligned with the adjacent strip, which creates waste at the top or bottom of each strip. A 12-inch repeat on an 8-foot wall wastes up to 12 inches per strip, requiring approximately 10 to 15 percent more wallpaper. Random or textured patterns with no repeat have zero matching waste.
Should I subtract windows and doors from my wallpaper calculation?
Standard practice is to deduct approximately 15 square feet for each standard window and 21 square feet for each standard door. However, many professionals recommend not deducting for openings smaller than a standard door because the extra wallpaper provides insurance against mistakes and matching issues. For rooms with very large windows or sliding glass doors, subtract their full area to avoid over-ordering significantly.
How accurate are the results from Wallpaper Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
How do I interpret the result?
Results are displayed with a label and unit to help you understand the output. Many calculators include a short explanation or classification below the result (for example, a BMI category or risk level). Refer to the worked examples section on this page for real-world context.