Wallpaper Calculator — rolls for a wall

How it works

Wallpaper is sold in rolls. To find how many, divide the wall area by the usable coverage of one roll, adding a waste allowance:

rolls = ⌈area × (1 + waste) ÷ roll coverage⌉

A standard single roll contains more paper than it covers, because you lose some to trimming and pattern matching — the usable coverage is around 28 square feet per single roll (double rolls cover about twice that). Coverage is an input, so use the figure for your paper.

Wallpaper uses a higher waste allowance than paint — 15% or more — because patterned papers must be aligned at the seams, and a larger pattern repeat wastes more. Buy all your rolls from the same batch (dye lot) so the colors match, and round up to whole rolls.

Worked example

A room with 400 sq ft of wall, at a 15% waste allowance and 28 sq ft usable per roll, needs (400 × 1.15) ÷ 28 = 16.4 → 17 rolls. Using double rolls (56 sq ft) halves that to ⌈460 ÷ 56⌉ = 9 rolls. A 150 sq ft feature wall needs ⌈172.5 ÷ 28⌉ = 7 rolls.

Frequently asked questions

How many rolls of wallpaper do I need?

Divide the wall area (plus waste) by the usable coverage per roll and round up: rolls = ⌈area × (1 + waste) ÷ roll coverage⌉. For 400 sq ft with 15% waste and 28 sq ft per roll, that is 17 rolls.

How much wall does one roll of wallpaper cover?

A single roll covers roughly 28 usable square feet — less than the paper it contains, because of trimming and pattern matching. Double rolls (sold as one long roll) cover about 56 sq ft. Check your roll's stated coverage and enter it.

Why is the waste allowance higher for wallpaper?

Patterned wallpaper must line up at every seam, so each strip is trimmed to match the one beside it, wasting part of the repeat. The larger the pattern repeat, the more you waste — allow 15% for small patterns and 20% or more for large repeats.

What is a dye lot and why does it matter?

A dye lot (or batch) is a single production run. Colors can shift slightly between lots, so rolls from different batches may not match on the wall. Buy all your rolls at once from the same lot, and round up so you do not run short mid-job.

How do I measure the wall area?

Multiply each wall's width by its height and add them up. You can leave doors and windows in for a safety margin, or subtract large openings. The pattern-matching waste allowance covers the trimming either way.

What about the ceiling or borders?

This sizes the wall rolls only. A papered ceiling is a separate area, and decorative borders are measured by length (the room perimeter). Calculate those separately from the main wall count.