How this calculator works. Wall area = perimeter × height, minus half a standard opening per door/window (you lose full strips around openings, so we don't subtract their full area). Rolls = area ÷ (roll coverage × pattern factor). The factors — 100% random match, 85% repeats to 12", 73% repeats 12–24" — reflect the strip length lost to aligning the pattern, per standard wallcovering-industry estimating practice.
Why wallpaper estimates go wrong
Wallpaper isn't paint: you can't stretch it, and you can't buy "a bit more" later with confidence — like tile, it's printed in batches ("run numbers"), and a different run has visibly different color. The whole game is buying enough of one run the first time. That's what the pattern-repeat factor protects: a 24-inch repeat means every strip must start at the same point in the pattern, and the offcut above that point is waste.
Straight-match patterns waste less than drop-match; the label tells you which you have, along with the repeat length and roll coverage. Trust the label's numbers over any generic chart — including ours — and enter them in advanced settings.
Rough roll guide (8-ft walls, US double rolls)
| Room | No repeat | Large repeat |
|---|---|---|
| 10×10 room | 5 rolls | 7 rolls |
| 12×12 room | 6 rolls | 8 rolls |
| Single accent wall (12 ft) | 2 rolls | 3 rolls |
Buying tips
Buy all rolls at once and check the run number on every label matches. Keep one uncut spare roll — wallpaper repairs need matching paper, and patterns get discontinued fast. Peel-and-stick papers follow the same math but forgive mistakes; traditional pasted paper does not, so lean toward the extra roll.
Common questions
Single rolls or double rolls?
US wallpaper is priced per single roll but sold in double-roll bolts — a marketing quirk that confuses everyone. Our calculator counts physical double rolls. When comparing prices, always confirm which unit the price is per.
Do I subtract windows and doors?
Partially. You lose most of a strip's width around openings anyway, so full subtraction under-buys. We credit half a standard opening each — the common estimator's compromise.
What is drop match vs straight match?
Straight match: the pattern aligns at the same height on every strip. Drop match: alternate strips shift by half the repeat — which wastes more paper. If your label says drop match with a large repeat, use our 12–24" setting even for a smaller repeat.
Can I wallpaper over old wallpaper?
One clean, well-adhered layer can sometimes be papered over, but pros strip it — trapped moisture bubbles both layers. Textured or vinyl paper must always come off first.