Wallpaper
Perimeter becomes rolls with pattern waste figured — and openings deducted before you pay for paper that hangs behind a door.
Your buy list
0
single rolls to buy- Gross wall area
- —
- After openings
- —
- With pattern waste
- —
Order every roll from one dye lot — check the run number on each bolt.
The pattern tax
Paint covers whatever it touches; wallpaper has to line up with itself every 20-some inches. Each strip gets cut from a longer length so the motif meets its neighbor exactly, and the trimmed-off band between strips is the pattern tax — commonly 15% of your net wall area.
Openings come off first because they're real: nobody papers behind a door. In a small powder room, one deducted doorway can be the difference between four rolls and five.
Drop matches change everything
Half-drop and three-quarter-drop patterns alternate the alignment of successive strips, which pushes waste toward 20–25%. If your paper's label shows a drop match, raise the waste box accordingly before you order.
On the counter
The assumptions this calculator ships with — every one is adjustable in the form.
- Roll coverage
- 56 sq ft usable per US double roll
- Pattern waste
- 15% on top of net area for match trimming
- Openings
- Standard door = 21 sq ft, window = 15 sq ft, both adjustable by count
Questions from the aisle
How much wall does a roll cover?
A US double roll is about 56 square feet usable after pattern trimming. European single rolls run closer to 28 — the calculator assumes 56; halve your entry if the label says European.
Why 15% waste for wallpaper?
Strips must be cut longer than the wall so patterns align at every seam, and each strip trims off a repeat or two. Straight-match papers waste less; large-drop repeats waste more.
Do doors and windows get deducted?
Yes, above — a standard door counts as about 21 square feet and an average window 15. Deducting them matters most in small rooms where one opening can save a whole roll.
Should I order all rolls at once?
Always — dye lots vary between print runs, and a mismatched seam shows forever. Buy the full count plus one spare roll from the same lot and keep the labels.
The reasoning behind this one
How to measure a room
Where the assumptions above come from, what changes them, and the mistakes that cost a second trip. Free to read, no account needed.