How Much Wallpaper Do I Need? Rolls, Repeats and the Formula

Published 2026 ? 4 min read

Wallpaper math is trickier than paint because of pattern repeats ? each roll has to line up with the next, which costs extra paper. Here's how the pros estimate it.

The calculation

Measure the perimeter of the room (add up all wall lengths) and multiply by the wall height. Subtract doors and windows. Divide by the coverage of a double roll (about 56 square feet after pattern waste). That's your roll count.

Pattern repeats change everything

• Plain / no repeat: standard coverage, minimal waste.
• Small repeat (under 12 in): add ~10%.
• Large repeat (12 in+): add 20?30% ? every strip uses extra paper to match.

Buy extra from the same batch

Wallpaper dye lots differ between batches. Buy 10?20% extra up front and return what you don't use, rather than risk a mismatched second order.

Run the numbers

Use the wallpaper calculator ? enter room dimensions and door/window areas, and it returns the double rolls needed.