You enter room length, width, wall height, and the number of doors and windows. The tool calculates the room perimeter, multiplies by wall height for gross wall area, then subtracts standard opening allowances. It divides the remaining area by the usable coverage of each roll (adjusted for pattern-repeat waste) and rounds up to whole rolls.
Yes, most professionals recommend purchasing one or two extra rolls for trimming waste, cutting errors, and future repairs. Wallpaper dye lots can vary, so buying enough from one batch helps ensure color consistency.
Pattern repeat is the vertical distance between identical points in a wallpaper design. You must align each strip to match the pattern, which wastes material. A "small" repeat is typically under 12 inches; "large" repeats exceed 12 inches and require more waste allowance.
American single rolls are typically 20.5 inches wide, while European and commercial rolls are often 27 inches. Check the label on your wallpaper before ordering — using the wrong width will give inaccurate results.
No, this calculator assumes four flat rectangular walls of equal height. For accent walls, enter just that wall's length as both length and width with the opposite dimension set to zero. Sloped ceilings require manual adjustment.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.