Wallpaper Calculator
Calculate how many rolls you need for your room
You're standing in the wallpaper aisle (or scrolling through an online store) trying to figure out how many rolls to order.
Wallpaper math seems simple until you factor in doors, windows, pattern repeats, and single vs. double rolls. One wrong assumption, and you’re short or drowning in excess.
A wallpaper calculator handles all of this. You enter your room dimensions, wall height, the number of doors and windows, and the roll specifications. It tells you exactly how many rolls to buy, including a waste allowance.
How the WallPaper Calculator Works
The process has five steps: calculate the perimeter, find the total wall area, subtract openings, divide by what one roll covers, and add waste.
A Worked Example
Your room is 12 x 14 feet with 8-foot walls. It has 2 standard doors (3' x 7') and 3 standard windows (3' x 5').
Step 1: Calculate the perimeter.
Perimeter = 2 x (12 + 14) = 52 feet
Step 2: Find the total wall area.
Wall area = Perimeter x Wall height = 52 x 8 = 416 square feet
Step 3: Subtract openings.
- 2 doors: 2 x (3 x 7) = 42 sq ft
- 3 windows: 3 x (3 x 5) = 45 sq ft
- Total openings: 87 sq ft
Net wall area = 416 - 87 = 329 square feet
Step 4: Adjust for pattern repeat.
Add a small allowance for matching patterns:
Adjusted area = 329 x 1.03 = 338.9 sq ft
Step 5: Divide by roll coverage.
A standard American double roll covers approximately 57.75 square feet (it's typically 21 inches wide and 33 feet long).
Rolls needed = 338.9 / 57.75 = 5.87 rolls
Step 6: Round up and add waste.
Always round up. You can't buy 0.87 of a roll. And add 10-15% for cutting waste, mistakes, and future repairs.
5.87 rounded up = 6 rolls, plus 15% waste = 6 x 1.15 = 6.90 or 7 rolls
You need 7 double rolls for this room.
How to Interpret Your Result
If the calculator says 3-5 rolls: You're covering a small room (bathroom, powder room, or a single accent wall). Double-check that you've entered all four walls if you're doing the whole room.
If it says 6-10 rolls: This is the typical range for a standard bedroom or living room. Most rooms with 8-foot ceilings and a couple of windows fall here.
If it says 10+ rolls: You’re likely covering a large room, tall ceilings, or a wallpaper with a big pattern repeat. Spaces like cathedral ceilings or open floor plans can easily require 15+ rolls.
If the number seems high: Check if it’s single or double rolls. A single covers about 28 sq ft, a double about 56—so 16 singles equals 8 doubles.
Some Questions You May Have
What's the Difference Between Single and Double Rolls?
A single roll of standard American wallpaper is about 20.5 inches wide and 16.5 feet long, covering approximately 28 square feet. A double roll is the same width but 33 feet long, covering about 56 square feet.
How Much Extra Should I Buy for Pattern Matching?
For wallpaper with a pattern repeat under 12 inches, add 10–15%. For repeats of 12–24 inches, add 15–20%, and for very large repeats over 24 inches, add 20–25%. Larger repeats create more waste because each seam must align with the pattern.
Can I Wallpaper Over Textured Walls?
It's not recommended. Wallpaper adheres best to smooth surfaces. Light texture (like orange peel) might work with thick wallpaper, but heavy texture (like knockdown or popcorn) can show through and cause adhesion issues.
How Do I Calculate for an Accent Wall Only?
Measure just the wall’s width and height, subtract any doors or windows, divide by roll coverage, and add waste. For a 12' × 8' accent wall with no openings: 96 ÷ 50 = 1.92, rounded up to 2 rolls. Add one for waste, totaling 3 double rolls.
What If My Walls Aren't Straight?
Use a level and a plumb line to establish a true vertical before hanging the first strip. You may need to overlap strips slightly or trim at corners. This can increase waste by 5-10%, so factor that into your roll count.
Should I Buy All My Rolls at Once?
Absolutely. Wallpaper comes in batches, and colors can vary slightly between them. Buying 6 rolls now and 2 later could mean the extra rolls are from a different batch with a slightly different shade.
Related Calculators / Articles: