Ordering wallpaper starts with a simple question: how much do you actually need? Measuring the walls is an important first step, but wallpaper quantity is not based on square footage alone. Roll dimensions, pattern repeat, matching requirements, doors and windows, and the shape of the room can all affect the final amount.
Taking careful measurements before ordering can help you avoid running short halfway through installation or buying considerably more than the project requires. Once you have chosen a design from Randall’s wallpaper selection, the exact specifications of that wallpaper can be used to calculate a more accurate quantity.
What Measurements Do You Need Before Buying Wallpaper?
Start by measuring the height and width of every wall you plan to cover. Measure each wall separately rather than assuming opposite walls are identical, particularly in older homes where dimensions can vary slightly.
For each wall, record:
- The full width of the wall
- The height from floor to ceiling
- The dimensions of doors
- The dimensions of windows
- Any large built-in features that will not be wallpapered
- Sloped ceilings, alcoves, bump-outs, or other unusual areas
It is useful to keep these measurements together with a simple sketch of the room. You do not need an architectural drawing. A basic diagram showing which measurement belongs to each wall can make the calculation much easier when you are comparing wallpaper options.
If you are still choosing a design, Randall’s Ottawa wallpaper collection can help you explore different styles before working out the final order.
How Do You Calculate the Square Footage of a Wall?
For a basic rectangular wall, multiply the width by the height.
For example, a wall that is 12 feet wide and 8 feet high has:
12 × 8 \= 96 square feet
Repeat this calculation for every wall you plan to cover and add the totals together.
This gives you the approximate wall area, but it should not be treated as the final wallpaper quantity. Wallpaper is installed in vertical strips, and the number of usable strips that can be cut from each roll matters just as much as the total square footage.
That distinction becomes especially important when the wallpaper has a large pattern repeat.
Should You Subtract Windows and Doors?
You can account for large openings, but it is usually better not to reduce the order too aggressively.
Wallpaper around windows and doors still has to be cut and aligned, and those areas can create additional waste. A large patio door may noticeably reduce the amount of wall being covered, while a small window may not change the number of full-length strips you need very much.
For a rough initial calculation, measuring the complete walls gives you a useful starting point. Once the exact wallpaper has been selected, the room layout and openings can be considered more carefully.
Randall’s wallpaper specialists can also help customers calculate the quantity required once a specific paper has been chosen.
Why Does Wallpaper Roll Size Matter?
Not every roll of wallpaper has the same dimensions.
The width and length of the roll determine how many full-height strips can be cut from it. Two wallpapers covering a similar stated area may therefore produce different numbers of usable strips depending on their dimensions and pattern.
Before calculating the order, check the specifications for the exact wallpaper you are considering. Do not assume that a roll from one manufacturer will be the same size as a roll from another.
This is one reason it is helpful to choose the wallpaper before making the final quantity calculation rather than trying to determine an exact number of rolls while you are still browsing.
Randall’s carries established wallpaper brands and collections, including York Wallpapers, giving homeowners a wide range of patterns and scales to compare.
What Is a Wallpaper Pattern Repeat?
A pattern repeat is the vertical distance before a design begins repeating itself.
Some wallpapers have very small repeats, while others have large florals, geometrics, or decorative motifs that repeat over a much greater distance. During installation, adjoining strips need to line up so that the design continues correctly across the wall.
That matching process can require extra wallpaper.
For example, if your wall is eight feet high, you may assume that every strip only needs to be slightly longer than eight feet. With a large pattern repeat, however, each strip may need additional length so that the design aligns with the strip beside it.
The greater the repeat, the more important it becomes to calculate quantity using the actual wallpaper rather than square footage alone.
If pattern scale is still part of your buying decision, Randall’s guide to choosing the right wallpaper pattern and colour explains how pattern size can change the overall look of a room.
What Is the Difference Between a Straight Match and an Offset Match?
Wallpaper patterns can match from strip to strip in different ways.
With a straight match, the pattern typically aligns at the same height on neighbouring strips. With an offset or drop match, the design shifts between strips before repeating.
An offset match can require more material because each new strip may need to begin at a different point in the pattern.
This does not mean an offset pattern should be avoided. Many beautiful wallpapers use this type of repeat. It simply means the matching requirement needs to be included when determining how many usable strips you will get from each roll.
The manufacturer’s wallpaper specifications should identify the repeat and match type.
How Do You Estimate How Many Wallpaper Strips You Need?
After measuring the walls, determine the total width you need to cover and compare it with the width of the wallpaper.
For example, if the wallpaper is approximately two feet wide, a 12-foot wall would require roughly six vertical strips before accounting for corners, pattern matching, and other adjustments.
You can repeat this process for each wall and estimate the total number of full-height strips required.
The next step is determining how many usable strips can be cut from one roll. That depends on:
- Roll length
- Wall height
- Pattern repeat
- Match type
- Additional length needed for trimming
Once you know the required number of strips and the usable strips per roll, you can make a much more reliable estimate than you would from wall area alone.
How Much Extra Wallpaper Should You Order?
Some additional material is usually sensible because wallpaper installation involves cutting, trimming, and matching.
Extra material may be needed for:
- Pattern alignment
- Trimming at ceilings and baseboards
- Corners and architectural details
- Mistakes during installation
- Damaged sections
- Future repairs
How much extra you need depends on the particular design and room. A small, simple repeat generally creates less waste than a large or complicated pattern.
Rather than applying the same percentage to every wallpaper project, calculate the room around the actual paper you have chosen. This gives you a better idea of how much allowance is appropriate.
Why Is It Useful to Keep an Extra Roll?
If the budget and product availability allow, keeping some wallpaper after installation can be useful.
A section of wallpaper may eventually be damaged by furniture, moisture, children, pets, or renovation work. Having material from the original order can make a repair much easier.
Ordering replacement wallpaper years later may also be more complicated if a pattern has been discontinued or if there are slight differences between manufacturing batches.
Even a partial roll can be valuable for future repairs, so keep leftover pieces in a clean, dry place rather than discarding them immediately after the project.
What If the Room Has Sloped Ceilings or Unusual Walls?
Rooms with sloped ceilings, bay areas, alcoves, staircases, or architectural details require more careful planning.
In these spaces, square-foot calculations become less useful because each strip may need to be cut to a different length. Pattern matching can also create more waste than it would on four simple rectangular walls.
Measure the highest and widest points and keep detailed notes about the room layout. If the wallpaper is expensive or has a large repeat, professional quantity calculation can be worthwhile before placing the order.
Randall’s offers décor consultations for homeowners who want guidance while planning a larger decorating project.
Should You Measure an Accent Wall Differently?
The basic measuring process is the same, but accent walls can be easier to calculate because you are dealing with one defined area.
Measure the full width and height of the wall, then check how many wallpaper widths are needed across it. From there, determine how many full-height strips can be cut from each roll after accounting for the pattern repeat.
Do not assume that a single roll will automatically cover a feature wall. A large wall, narrow wallpaper, or substantial pattern repeat may require more material than expected.
Wallpaper can also be used in ways other than covering all four walls. Randall’s article on the beauty of traditional wallpaper looks at how wallpaper can add texture and character to an interior.
Should You Buy Wallpaper Before or After Measuring?
Take preliminary measurements first, then choose the wallpaper, and finally calculate the exact order.
That sequence usually works best because your initial measurements tell you approximately how large the project is, while the specifications of the chosen wallpaper determine the final quantity.
In practical terms:
- Measure the room.
- Choose the wallpaper.
- Check the roll dimensions and pattern repeat.
- Calculate the number of required strips.
- Account for pattern matching and waste.
- Confirm the quantity before ordering.
This approach is more reliable than buying a general number of rolls based solely on the size of the room.
Can Randall’s Help Calculate How Much Wallpaper You Need?
Yes. Randall’s wallpaper specialists can help customers calculate the quantity needed once they have selected the wallpaper they want.
That can be especially useful for wallpapers with substantial pattern repeats or rooms with unusual dimensions.
Seeing wallpaper in person can also help with the earlier stages of the decision. Samples allow you to compare colour, scale, texture, and how the design looks in the room before placing a larger order.
You can visit Randall’s showrooms with your measurements and discuss the project before ordering.
Final Thoughts
Calculating wallpaper is not simply a matter of dividing your wall area by the coverage printed on a roll. The most accurate estimate considers wall dimensions, roll size, strip length, pattern repeat, matching requirements, and the amount of material likely to be lost during trimming and installation.
Measure carefully before you shop, but wait until you have selected the exact wallpaper before finalizing the number of rolls. That small extra step can reduce waste while helping ensure you have enough material to complete the project without interruption.
Plan your wallpaper project with Randall’s: