Wallpaper Calculator
Rolls, strips, and cut lengths for any room or accent wall — with the pattern repeat handled the way a paperhanger does it, not a rough square-foot guess.
Openings aren't deducted — see the FAQ for why.
Check the label — length varies by brand.
Printed on the label. 0 for solids, textures, and random-match papers.
You need
Enter dimensions
| Detail | Amount |
|---|---|
| Strips needed | — |
| Cut length per strip | — |
| Strips per roll | — |
Mid-range papers commonly run $40–$100 per double roll.
How to Calculate Wallpaper
Wallpaper math is strip counting, not square footage — because every strip must be a full-height cut that lines up with its neighbor:
- Cut length: wall height plus 4″ trim allowance. With a pattern repeat, round that up to a whole number of repeats.
- Strips needed: wall (or perimeter) width ÷ roll width, rounded up.
- Strips per roll: roll length ÷ cut length, rounded down.
- Rolls: strips needed ÷ strips per roll, rounded up — plus one spare from the same batch.
Wallpaper formulas
Cut length = ceil((height + 4″) ÷ repeat) × repeat
Rolls = ceil( ceil(width ÷ roll width) ÷ floor(roll length ÷ cut length) )
Worked example — 12 × 12 room, 8 ft walls, 20.5″ × 33 ft rolls, no repeat: perimeter 576″ ÷ 20.5″ = 29 strips; cut length 100″ → 3 strips per roll → 10 double rolls.
Why the Pattern Repeat Changes Everything
Same 12 × 12 room, same rolls — watch the roll count climb with the repeat:
| Pattern repeat | Cut length | Strips per roll | Double rolls |
|---|---|---|---|
| None (0″) | 100″ | 3 | 10 |
| 12″ | 108″ | 3 | 10 |
| 18″ | 108″ | 3 | 10 |
| 25″ | 100″ | 3 | 10 |
| 36″ | 108″ | 3 | 10 |
On 8 ft walls a 33 ft roll absorbs most repeats. The trap is 9–10 ft ceilings: cut lengths past 132″ drop you to 2 strips per roll, and the roll count jumps 50%.
Tips Before You Order
- Same batch number on every roll. Dye lots shift between print runs; mismatched rolls show as a color seam.
- Buy one spare roll. Future repairs need paper from your run — it won't exist later.
- Check single vs. double roll pricing. US papers are priced per single but sold per double — a "$30" paper is a $60 bolt.
- Drop-match patterns waste more. If the label says half-drop, treat the effective repeat as 1.5× the stated figure for estimating.
- Prime the wall. Wallpaper primer (sizing) makes hanging easier and future removal possible.
Frequently Asked Questions
How many rolls for a 12×12 room?
10 standard double rolls at 8 ft ceilings with no repeat; large repeats or taller walls push it to 12+.
What is a pattern repeat?
The vertical distance before the design repeats. Strips are cut in whole repeats so they align — the offcut is unavoidable waste you must buy.
Single roll vs. double roll?
Priced per single, sold per double. A metric double roll is 20.5″ × 33 ft ≈ 56 sq ft gross.
Do I subtract doors and windows?
Traditionally no — you still need full-height strips around openings, and pattern-matched offcuts rarely reuse. Only deduct very large openings.
How many strips per double roll?
3 on standard 8 ft walls; 2 once the cut length passes ~11 ft (tall ceilings or big repeats).
Should I buy extra?
One spare roll, same batch. Unopened rolls usually return; a missing repair roll never does.
References
- Wallcoverings Association — installation and estimating resources: wallcoverings.org
- York Wallcoverings — roll dimensions and hanging guides: yorkwallcoverings.com
- Graham & Brown — pattern match types explained: grahambrown.com