How to Use the Wallpaper Calculator
Use the calculator to estimate rolls from your wall measurements and the figures printed on the roll label.
- Select Unit system:
Imperial (ft / in)orMetric (m / cm). - Enter Total wall width, Wall height, door and window counts and widths, Roll width, Roll length, Pattern repeat, and Waste / overage %.
- Select Calculate to show the estimate, formula, assumptions, and intermediate values.
- Select Reset to clear wall dimensions, restore Imperial mode and its defaults, clear errors, and hide the result.
What the Result Calculates
The calculator first subtracts door and window deductions from the total wall width. It then estimates the number of full-height drops and rolls:
Drop length = Wall height + one full Pattern repeatfor every calculated drop when the repeat is above 0.- When Pattern repeat is 0, it adds a fixed trim allowance of 4 in in Imperial mode or 10 cm in Metric mode. This allowance is not an editable control.
Drops per roll = floor(Roll length / Drop length)Strips needed = ceil(Net wall width / Roll width)- Waste is applied to the strip count, then
Rolls needed = ceil(Strips with waste / Drops per roll).
The result shows rolls to buy, strips with waste, usable drops per roll, net wall width, the formula, assumptions, and intermediate values.
Units, Openings, and Roll Details
- Imperial uses feet for wall width, wall height, and roll length; it uses inches for roll width, pattern repeat, and door/window widths.
- Metric uses meters for wall width, wall height, and roll length; it uses centimeters for roll width, pattern repeat, and door/window widths.
- Total wall width is the combined linear width of the walls being papered, not wall area. Door and window deductions use count multiplied by average width.
- Set opening counts to 0 if the net wall width you entered already excludes those openings.
- Changing Unit system resets roll width, roll length, pattern repeat, and default opening widths.
Assumptions and Limitations
Inputs are checked against numeric ranges, including wall width 1–1,000, wall height 1–100, waste 0–50%, opening counts 0–200, opening widths 0–200, roll width 1–200, roll length 1–500, and pattern repeat 0–200 in the selected units. Door and window deductions cannot equal or exceed wall width, and the drop length cannot exceed roll length.
- The visible door and window count fields use a step of 1, but the script accepts decimal counts and displays them rounded to zero decimals.
- The model uses straight, full-height drops in one continuous run per wall.
- One calculation can use any single width, including a feature wall, but it does not separately model multiple wall sections with different dimensions or pattern repeats.
- It does not model chimneys, alcoves, sloped ceilings, pricing, supplier data, brand-specific hanging instructions, or certified decorating advice.
Copying or Downloading the Result
Copy result uses clipboard access. If that access is unavailable, the calculator displays a manual-copy fallback message. Download result (.txt) creates a plain-text file named wallpaper-calculator-result.txt.
Privacy and Page-Level Data Behavior
The calculator performs its arithmetic locally and does not transmit calculator input values. Separate shared page assets load Ahrefs and Google Analytics scripts, and the subscription form sends subscription email data to /assets/subscribe.php.
Frequently Asked Questions
What is the wallpaper roll formula?
Net wall width = Wall width - (Doors x Door width) - (Windows x Window width). Drop length = Wall height + Pattern repeat (or + a trim allowance if there is no repeat). Drops per roll = floor(Roll length / Drop length). Strips needed = ceil(Net wall width / Roll width). Strips with waste = ceil(Strips needed x (1 + Waste % / 100)). Rolls to buy = ceil(Strips with waste / Drops per roll).
Why does pattern repeat increase the number of rolls needed?
The calculator adds one full pattern repeat to the wall height for every calculated drop before working out how many drops fit on a roll. A longer repeat means fewer usable drops per roll and may increase the number of rolls needed.
What wall width should I enter?
Enter the total linear width of wall you plan to paper - the sum of each wall's width (the room's papering perimeter), not the wall area. Use the door and window fields to deduct opening widths, or set their counts to 0 if you've already measured net wall width.
What units are supported?
Imperial mode uses feet for wall width, height, and roll length, and inches for roll width, pattern repeat, and door/window width. Metric mode uses meters for wall width, height, and roll length, and centimeters for roll width, pattern repeat, and door/window width. Switch with the unit-system selector.
Does this tool fetch live pricing or give certified advice?
No. It performs a single, transparent calculation using only the wall, roll, and pattern-repeat figures you type in. It does not fetch wallpaper prices or brand-specific roll data, and it is not certified decorating advice.