Enter the height of the walls you are papering and the width of each wall. Use the Add Wall button for rooms with more than one wall, and the calculator will sum the total wall width for you.
Add one row per wall you plan to cover. Widths are added together to get the total wall width.
Enter the number of standard doors and windows in the area you are covering. A standard door is assumed to be 21 square feet and a standard window is assumed to be 15 square feet, and these are subtracted from your total square footage to cover.
These numbers are printed on the wallpaper label or the manufacturer's product page. Pattern repeat should be 0 for solid colors or random match designs.
The Complete Guide to Calculating Wallpaper Rolls
Buying wallpaper is one of those projects where guessing leads to either an expensive last-minute trip back to the store, or a stack of unused rolls sitting in a closet for years. The good news is that the math behind a roll estimate is straightforward once you understand a handful of terms: drop, pattern repeat, and usable yield. This guide walks through how the calculator above turns your room measurements and roll specifications into a single number, and explains why small details, like a 12 inch pattern repeat, can have an outsized effect on your final total.
How to Use This Tool
Start by choosing whether you want to work in feet and inches or meters and centimeters using the unit toggle. Enter the height of the wall you are covering, then add a row for each wall using the Add Wall button and enter its width. The calculator adds all of your wall widths together automatically. Next, enter how many standard doors and windows are in the space, since each one reduces the total square footage that needs covering. Finally, enter the roll length, roll width, and pattern repeat from the label of the wallpaper you plan to buy, and adjust the waste factor slider if your room has unusual angles, many corners, or a particularly large pattern repeat. The results update instantly as you type, with no button to press.
The Drop Calculation
A drop is one full vertical strip of wallpaper, cut to the height of your wall. The length of a single drop is not simply your wall height, however. It is your wall height plus the pattern repeat, because each new drop needs an extra section of pattern at the top so it can be aligned with the drop next to it. A wall that is 8 feet, or 96 inches, tall with a 12 inch pattern repeat needs drops that are 108 inches long, even though only 96 inches of that drop will end up visible on the wall once it is trimmed top and bottom.
Roll Yield and Total Drops
Once you know the drop length, you can figure out how many drops fit inside one roll. This is the roll length divided by the drop length, rounded down, because a partial drop at the end of a roll usually cannot be used. This number is called the roll yield, or usable yield. Separately, the calculator figures out how many drops you need in total by dividing your total wall width by the roll width and rounding up, since you cannot hang a fraction of a drop. Dividing the total drops needed by the roll yield, and rounding up again, gives you the base number of rolls required before any waste is added.
Why Doors, Windows, and Waste Still Matter
Doors and windows reduce the total square footage you ultimately need to cover, and this calculator subtracts a standard 21 square feet per door and 15 square feet per window to show a more realistic total square footage figure alongside the raw wall square footage. In practice, openings rarely let you skip an entire drop, since most installers still run a continuous drop past a door or window opening and trim around it. That is one reason the waste factor exists. A waste factor between 10 and 20 percent absorbs the gap between the theoretical minimum and the real-world result, covering pattern matching at corners, trimming around outlets and trim, and the inevitable mis-cut strip or two that happens on almost every project.
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The pattern repeat is the vertical distance before a design motif repeats itself, and it directly controls how many usable drops you can cut from a single roll. Every drop you hang must line up with the one next to it, so each cut has to start at the same point in the pattern. If the pattern repeat is large compared to your roll length, a lot of paper at the end of each drop gets wasted because the next full repeat would not fit, or because that leftover piece cannot be matched anywhere else. A solid color or random match design with a pattern repeat of 0 wastes almost nothing, while a large repeat, such as 24 inches, can sometimes drop your usable yield from 4 drops per roll down to just 3. That single drop of difference can add several rolls to your total order for a large room, so always enter the actual pattern repeat printed on the wallpaper label rather than leaving it blank.
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A single roll is a unit of measurement, typically around 27 to 36 square feet of material, but most modern wallpaper is no longer sold as one single roll on its own. Instead, manufacturers package two single rolls together into one continuous bolt, commonly called a double roll. When a product label says it covers a certain number of single roll equivalents, that usually describes the total square footage inside the double roll bolt you are actually buying. This matters because if a calculator or a store clerk quotes you a number of single rolls, you may need to divide that figure by two to know how many physical double roll bolts to purchase. Always check whether the roll length and width you enter into this calculator match the actual dimensions of the bolt you plan to buy, since that is what determines your real usable yield per roll.
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It depends on how precise you want to be, and on how your walls are shaped. Doors and windows do reduce the actual square footage of wallpaper needed, and this calculator subtracts a standard 21 square feet per door and 15 square feet per window from your total wall area so the square footage figure is more realistic. However, openings rarely save you a full roll, because wallpaper is hung in continuous vertical drops across the entire wall width, and a door or window in the middle of a wall usually still requires that drop to be cut to full height above and below the opening, or a fresh drop started on either side. For that reason, many professional installers calculate the number of rolls based on the gross wall width and height, then treat any savings from openings as a buffer that helps absorb mistakes and pattern matching waste rather than as a roll they can skip entirely.
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A waste factor is an extra percentage added on top of your base roll calculation to cover the realities of an actual installation. Even with careful planning, every project loses some material to pattern matching at corners, trimming around outlets and trim work, mistakes during the first few cuts while you get a feel for the paper, and small variations in wall height from floor to ceiling. A 10 percent waste factor is the standard starting point for most rooms, while rooms with many corners, large pattern repeats, or a first-time installer should lean toward 15 to 20 percent. Buying slightly more wallpaper up front is almost always cheaper and less stressful than running short partway through a wall, especially if the dye lot or run number changes between purchases and the new rolls do not match the old ones exactly.
Planning Note: This calculator provides an estimate based on the measurements and roll specifications you enter. Always round up to the nearest full roll, buy from a single run or lot number when possible, and check with your supplier's return policy before purchasing.