Wallpaper Calculator
Wallpaper math is strip math, not area math: count the strips your walls need, see how many strips each roll yields, and get the roll count — pattern repeat included. Runs 100% in your browser.
Wallpaper Calculator
About this wallpaper calculator
Wallpaper is sold by the roll but hung by the strip, and that is why area math misleads: a roll's gross square footage ignores the trimming every strip needs and the pattern alignment every patterned strip wastes. This calculator counts strips first (wall length divided by roll width, rounded up), then divides by how many full strips each roll yields — which shrinks as pattern repeat grows. Our wallpaper guide covers measuring, single vs double rolls, and the dye lot rule in detail.
Pattern repeat is the hidden cost. A strip must be cut so its pattern aligns with its neighbor, so each strip effectively consumes wall height plus up to one full repeat. On an 8-ft wall, a 24-inch repeat turns a 33-ft roll from 4 strips into 3 — a 25% jump in rolls for the same walls. Half-drop patterns (alternate strips offset by half a repeat) waste the most of all.
Measure walls, not floors: add up every wall's width, multiply by ceiling height, and enter that total length. Doors and windows are not subtracted here — the offcuts around openings rarely reuse cleanly, so leaving them in acts as your waste buffer. If you measured net area instead, add a roll.
How to use
- Add up the width of every wall you are papering and enter the total in feet.
- Enter the wall height in feet and your roll's width and length (US single rolls are typically 20.5 in × 33 ft).
- Enter the pattern repeat from the label in inches, or 0 for plain/random-match paper.
- Optionally enter the price per roll, then press Calculate.
Good to know
- Does not subtract doors and windows — the offcuts around openings act as waste buffer. For heavily interrupted walls, the count runs slightly high (safe direction).
- Assumes one consistent ceiling height; sloped ceilings and stairwells need manual layout at the tallest point.
- Double rolls are just longer rolls — enter 66 ft as the roll length and the math works the same.
Frequently asked questions
How many rolls of wallpaper do I need for a 12x12 room?
A 12×12 room has 48 ft of wall. At 8-ft ceilings with 20.5-in rolls, that is 29 strips and 4 strips per 33-ft roll — 8 rolls for plain paper. A large pattern repeat drops it to 3 strips per roll, so 10 rolls.
How many square feet does a roll of wallpaper cover?
A US single roll (20.5 in × 33 ft) is 56 sq ft gross but covers about 50 sq ft usable after trimming. A double roll covers about 100 sq ft usable. Pattern repeat reduces usable coverage further.
What is pattern repeat in wallpaper?
The vertical distance before the design repeats. Each strip must align with its neighbor, so larger repeats waste more paper — a 24-inch repeat can waste a foot or more per strip.
Should I subtract doors and windows when measuring wallpaper?
This calculator leaves them in on purpose: offcuts around openings rarely reuse cleanly. If you already subtracted them, add one roll back as your buffer.
What is a double roll of wallpaper?
One continuous roll roughly double the length of a single roll (~66 ft vs 33 ft) at the same width — not two rolls. Enter 66 ft as the roll length above.