Wallpaper Calculator

How wallpaper rolls are calculated

Wallpaper math starts with the full wall surface and subtracts what won't be papered:

Wall area = room perimeter × wall height = 2 × (length + width) × height
Papered area = wall area − (doors × 21 sq ft) − (windows × 15 sq ft)
Rolls = papered area ÷ usable coverage per roll, rounded up

A roll's gross coverage is its width × length: the common 20.5 in × 33 ft double roll covers about 56 sq ft on paper. In practice you lose some to trimming each strip top and bottom and to aligning the pattern repeat, so this calculator scales the gross coverage down by the allowance you pick (10% is typical; choose 15% for a large pattern repeat). It always rounds up to whole rolls — running one strip short with a mismatched dye lot is far worse than having a spare roll.

Roll sizes vary a lot: American rolls are often 27 in wide (33 ft for a double roll, about 74 sq ft gross); European rolls are usually 20.5 in × 33 ft; some designer papers are narrower still. Always enter the width and length printed on the label of the paper you're actually buying, and buy all rolls from the same dye lot (run number) so colors match across strips.

Accent wall only? The perimeter formula assumes four walls, so for a single feature wall do the short version by hand: wall length × height, minus any door or window on it, divided by the usable coverage per roll shown above — and still round up. For anything unusual (stairwells, sloped ceilings, a wainscot line that stops the paper partway down), measure each section's area separately and add them before dividing.