1. Strips, not square feet. Wallpaper goes up in vertical strips. Each strip has to be the wall height plus about four inches of trim allowance, rounded up to a whole pattern repeat so the pattern lines up strip to strip. A 9-foot wall with a 24-inch repeat needs 120-inch strips, not 108.
2. Strips per roll. A double roll is usually 33 feet long. Divide by the strip length: 396 inches ÷ 120 = three usable strips per roll, and the leftover 36 inches is waste (or short pieces over doors).
3. Strips across the wall. Total wall width in inches ÷ roll width (20.5 inches on most American papers, 27 on some, 24 on murals) = strips needed. We subtract half a strip per full-height door and nothing for windows — the pieces above and below a window still come out of a full strip.
4. Rolls. Strips needed ÷ strips per roll, rounded up, plus 10% overage, all ordered together from one dye lot. Reorders rarely match.
Half-drop match. Every other strip starts half a repeat lower, so we allow an extra half repeat per strip. Random match (most grasscloth and textures) has no repeat — enter 0.
Murals and panels are sized to your wall by the printer; send us the dimensions and we'll check the panel count instead.
Roll sizes vary by brand: check the product page for width, length and repeat. European rolls are typically 20.5 inches by 33 feet (about 56 square feet); some US heritage lines sell 27-inch by 27-foot rolls; print-on-demand houses sell 24-inch panels in fixed lengths.