Wallpaper Calculator
How many rolls — with pattern-repeat waste counted in. Free, instant, and private — everything runs on your device.
U.S. single roll ≈ 20.5 in
Often 33 ft per single roll
0 for random-match papers
Your wallpaper estimate
- Drops needed (room perimeter)
- 29
- Drops per roll
- 3
- Wall area after openings
- 381 sq ft
- Estimated cost
- $400
Wallpaper is bought in whole rolls, and pattern-repeat trimming wastes more than area math suggests — this counts the drops you can actually cut from each roll. Buy one extra roll for repairs and keep the batch number.
Wallpaper is the one wall covering where 'just buy the square footage' reliably leaves you short. Rolls come in fixed lengths, every drop has to start at the ceiling line, and any pattern that repeats forces you to waste an inch or a foot off each strip to line the design up. This calculator works the way a paperhanger does: it counts the full-height drops your room needs, works out how many drops you can cut from one roll after the pattern repeat, and turns that into rolls to buy.
Enter your room, your roll's real width and length (they're on the label), and the pattern repeat. You'll get the roll count, the coverage math behind it, and a cost — plus the reminder to buy one extra roll and record the batch number, because dye lots drift between print runs.
How it works
No black box — this is the exact math the calculator runs.
- Room perimeter = 2 × (length + width), in feet.
- Drops needed = perimeter ÷ roll width, rounded up — one full-height strip per roll-width of wall.
- Usable drop length = wall height + one pattern repeat (or a trim allowance for random-match papers).
- Drops per roll = roll length ÷ usable drop length, rounded down.
- Rolls = drops needed ÷ drops per roll, rounded up to whole rolls.
- Cost = rolls × your price per roll. Doors and windows are shown as reduced wall area but not subtracted from rolls, so pattern matching stays safe.
Last reviewed July 24, 2026 · Paint & Decor
Frequently asked questions
How many rolls of wallpaper do I need for a 12x12 room?
A 12×12 room with 9-foot walls has a 48-foot perimeter. With a standard 20.5-inch-wide, 33-foot roll and no pattern repeat, you need about 6 rolls. A large pattern repeat can push that to 7–8, which is exactly why the repeat field matters.
Should I subtract doors and windows from my wallpaper count?
Not from the roll count. Paperhangers hang full drops across openings and trim them out, because breaking the pattern to save a strip usually costs more in mismatched seams. The calculator shows the reduced wall area for reference but keeps the roll count safe.
What is pattern repeat and why does it waste wallpaper?
The pattern repeat is the vertical distance before the design starts over. To line up seams, each new drop has to begin at the same point in the pattern, so you trim up to one full repeat off every strip. A 20-inch repeat can add a whole extra roll to a big room.
How much extra wallpaper should I buy?
Buy one extra roll beyond the estimate and keep it unopened. Wallpaper is printed in batches (dye lots) that vary slightly, and the batch you bought will be gone when you need a repair. Record the batch number from the label with your leftover roll.