Wallpaper Calculator (Rolls Needed)

Wallpaper is sold in fixed-size rolls and hung as vertical strips, so the question isn't a single area ratio (this site's Paint Coverage calculator's question) but three ceiling-division steps: how many strips fit across the wall's total width, how many of those strips can be cut from one roll's length, and how many rolls that takes for every strip you need.

A patterned paper also needs its repeat to line up from strip to strip, which forces each strip to be cut to a whole number of pattern-repeat lengths — rounded up to at least the wall height, not exactly the wall height. A large repeat can therefore reduce how many strips fit on one roll even though the wall itself hasn't changed, which is why this calculator asks for the repeat separately rather than assuming a plain, unpatterned paper.

All dimensions are converted to a single unit (meters) before these ratios are computed, since the strips-per-roll and rolls-needed math is pure geometry with no unit-dependent physical constant — unlike, say, a formula involving gravity or density, consistent units are all that's required here.