Free estimate — verify against local code before building
Wallpaper Calculator
Enter wall width, height, and the roll and repeat from the label to get double rolls, strips, paste, and primer.
What this calculator includes
Wallpaper is ordered by usable strips, not square feet — and a pattern repeat quietly stretches every strip to a whole number of repeats, which can drop a full strip from every roll. This calculator cuts each strip with a 4-inch trim allowance, rounds it up to the repeat, handles straight and half-drop matches, credits half the width of doors and windows the way estimators actually do, and converts strips into double rolls, paste, and primer. Every assumption stays visible so you can check the math against the roll label.
How to use this wallpaper calculator
- 01
Measure the papered walls
Add the widths of every wall you plan to paper and measure the wall height. Count doors and windows — standard practice only deducts a half-width credit for generous openings, so small openings are safely ignored.
- 02
Copy the roll label
Enter the roll width, roll length (a double roll is standard in the US), the vertical pattern repeat, and whether the pattern is a straight or half-drop match. All four numbers are printed on the label or listing.
- 03
Check the strip math
The calculator cuts each strip at wall height plus 4 inches of trim, rounds it up to a whole repeat, and shows how many usable strips each roll yields. Watch this number — a large repeat can silently drop a strip per roll.
- 04
Order one dye lot
Order every roll from the same dye lot plus one spare roll for repairs. Lots vary slightly in color, and a mismatched replacement roll is visible on the wall.
Calculation sources and review
Primary references and formula assumptions are linked so you can verify them against the selected product, supplier, and adopted local requirements.
Internal formula review completed July 13, 2026. What this review covers
- Lowe's — wallpaper buying guide (opens in a new tab)
Roll sizing, match types, and single vs double roll conventions.
- Bob Vila — how to hang wallpaper (opens in a new tab)
Trim allowance, dye-lot, and installation practice.
- Wallcoverings Association (opens in a new tab)
Industry terminology for pattern repeat and match types.
Frequently asked questions
How many strips of wallpaper are in a double roll?
Divide the roll length by your cut strip length. A 33 ft (396 in) double roll yields 3 strips when strips cut at 100–132 inches, but only 2 strips once a pattern repeat pushes the cut past 132 inches. The calculator does this rounding for you.
How does pattern repeat change how much wallpaper I need?
Every strip must be cut to a whole number of repeats so the pattern aligns across seams. A 10 ft wall needs a 124 in strip, but with a 24 in repeat each strip is cut at 144 in — the same roll drops from 3 usable strips to 2, and the order can jump several rolls.
What is the difference between straight and half-drop match?
A straight match aligns the same pattern element at the ceiling on every strip. A half-drop staggers alternate strips by half a repeat, which averages about an extra quarter repeat of waste per strip. This calculator adds that average automatically.
Should I subtract doors and windows from a wallpaper estimate?
Only partially. Paper still runs above doors and above and below windows from full strips, so estimators credit roughly half the opening width. This calculator converts that half-width credit into whole strips and never deducts below one strip.
Why order an extra roll of wallpaper?
Dye lots vary, and a roll bought later almost never matches. Order all rolls from one lot plus one spare so future repairs and mistakes come from matching paper.