Before you even think about patterns, you need to know how much wallpaper your wall actually requires. Buying too little means you might not be able to finish the job, especially if the pattern needs matching and you can’t get more of the same dye lot. Buying too much means wasted money and materials.
Here’s the straightforward way to get it right every time.
Measure your wall height and width
Grab a tape measure. You’ll need two measurements for each wall you plan to cover: its height and its width. Measure from the baseboard (or floor if you don’t have one) all the way up to the ceiling. For width, measure from one corner to the other.
If your room has multiple walls to paper, measure each one individually. Don’t assume all walls are the same size, even in newer construction. Measure every single one.
Standard wall height in the US is typically 8 feet. However, you’ll find 9-foot and even 10-foot ceilings in many homes, especially in living rooms or newer builds. Measure yours to be sure.
Account for doors, windows, and other openings
For accurate wallpaper calculations, you need to subtract the areas of doors and windows from your total wall measurements. Measure the width and height of each door and window opening.
How to subtract openings:
- For windows: Measure the width and height of the glass area. Multiply these two numbers to get the square footage of the window.
- For doors: Measure the width and height of the door itself. Multiply these to get the square footage of the door.
Add up the square footage of all windows and doors on a given wall or in the room. This total will be subtracted from the total wall area later.
Calculate the total square footage of your walls
Now, multiply the height of a wall by its width to get its square footage. Do this for each wall you plan to cover.
Formula: Wall Height (ft) x Wall Width (ft) = Wall Square Footage (sq ft)
If you’re wallpapering an entire room, add up the square footage of all the walls.
Total Room Square Footage = Sum of all Wall Square Footage
Subtract openings from total wall area
Take the total square footage of your walls (either for a single wall or the whole room) and subtract the combined square footage of all doors and windows you measured earlier.
Net Wall Square Footage = Total Wall Square Footage – Total Openings Square Footage
This net square footage is the actual area you need to cover with wallpaper.
Understand wallpaper roll coverage
This is where things can get tricky if you’re not careful. Wallpaper is sold in rolls, and each roll covers a specific area. You need to know the dimensions of the wallpaper rolls you are considering.
Standard US wallpaper roll sizes:
- Single Roll: Approximately 20.5 inches wide by 33 feet long. This covers about 56 square feet.
- Double Roll: Twice the length of a single roll, so approximately 20.5 inches wide by 66 feet long. This covers about 112 square feet.
Important Note: Most wallpaper is now sold in ‘double rolls’ even if it’s labeled as a ‘single roll’ in older terminology. Always check the actual dimensions listed on the packaging or product description. It’s safer to assume you are buying a double roll unless specified otherwise.
Pattern repeat impacts coverage
The pattern repeat is the vertical distance on the wallpaper where the pattern starts to repeat. This is crucial because it dictates how much paper you waste when aligning patterns between strips.
Small pattern repeat (e.g., 0-6 inches): You’ll have less waste. A standard double roll might cover closer to 50-55 sq ft of actual wall space.
Large pattern repeat (e.g., 18-24 inches or more): You’ll have significantly more waste. A double roll might only cover 40-45 sq ft of usable wall space.
Always check the pattern repeat measurement on the wallpaper’s packaging or specifications. If it’s a large repeat, you’ll need more rolls than a simple square footage calculation suggests.
How to calculate the number of rolls needed
Once you know your net wall square footage and the usable coverage of a wallpaper roll (taking pattern repeat into account), you can calculate the number of rolls required.
Formula: Number of Rolls = Net Wall Square Footage / Usable Coverage per Roll (sq ft)
Round up to the nearest whole number. For example, if you need 2.3 rolls, buy 3.
Example calculation:
Let’s say you have a wall that is 8 ft high and 12 ft wide. There’s one window measuring 3 ft x 5 ft.
1. Wall Area: 8 ft (height) x 12 ft (width) = 96 sq ft.
2. Window Area: 3 ft (height) x 5 ft (width) = 15 sq ft.
3. Net Wall Area: 96 sq ft – 15 sq ft = 81 sq ft.
4. Usable Roll Coverage: Let’s assume a double roll with a medium pattern repeat covers about 50 sq ft of usable wall space.
5. Rolls Needed: 81 sq ft / 50 sq ft/roll = 1.62 rolls.
You would need to buy 2 double rolls of wallpaper for this wall.
Why you should always buy extra
It is almost always recommended to buy at least one extra roll beyond your calculated need. Here’s why:
- Mistakes during installation: Especially if you’re new to wallpapering, you might cut a strip too short, make a mistake aligning a pattern, or damage a piece.
- Future repairs: If you ever need to patch a small section due to damage (e.g., a scuff mark, a hole from a picture hook), having extra rolls from the same dye lot is invaluable. Trying to repair with paper from a different batch can result in a noticeable color difference.
- Pattern matching across doorways and corners: Sometimes, to get the pattern to align perfectly across complex architectural features, you might need to use more paper than a simple flat measurement suggests.
If you’re using a bold pattern or covering a large area, consider buying two extra rolls. It’s better to have a little left over than to run short.
Consider the wallpaper type
Different types of wallpaper have different installation challenges and yardage requirements.
Peel and stick wallpaper
This is often the most forgiving for DIYers. It typically comes in panels, making pattern matching easier. The rolls themselves are often wider and shorter than traditional wallpaper. Always check the manufacturer’s specific coverage details.
You can learn more about its benefits in our guide to easy peel and stick wallpaper, and discover the best high-quality peel and stick options available.
Traditional wallpaper (paste the wall/paste the paper)
These rolls can vary widely in size and pattern repeat. While the calculations above are a good starting point, always verify the specific roll dimensions and pattern repeat of the product you choose. Floral patterns, for instance, can sometimes have large repeats that increase waste, as seen in our guide to flowers on wallpaper.
Designer wallpaper collections
Brands like Rifle Paper Co. offer stunning designs. When choosing these, ensure you confirm the roll size and pattern repeat as they can differ from standard offerings. You can see some beautiful examples in our Rifle Paper Co. wallpaper showcase.
Common mistakes to avoid
1. Not measuring accurately: This is the cardinal sin. Measure twice, cut once is clichĂ© for a reason. Ensure you’re measuring height and width correctly, and don’t forget to account for obstructions.
2. Forgetting the pattern repeat: A large pattern repeat drastically reduces the usable square footage of a roll. Always factor this in, especially for wallpapers with large or complex designs.
3. Assuming all rolls are the same size: Roll sizes can vary by manufacturer and even by collection. Always check the exact dimensions and square footage coverage specified on the packaging.
4. Not buying enough extra: Running out of wallpaper mid-project is a nightmare. Always add at least one extra roll, and sometimes two for larger projects or complex patterns.
5. Ignoring the dye lot: If you need to buy more wallpaper later, make sure the new rolls are from the same dye lot as your original purchase. Different dye lots can have slight color variations that will be very noticeable on your wall.
Special considerations for specific areas
Ceilings: Wallpapering a ceiling is significantly more difficult and requires more paper due to awkward angles and the need for very precise cuts. Plan for extra waste.
Alcoves and built-ins: While small, these areas require careful measuring and cutting. They can add up in terms of wasted paper when you’re trimming strips to fit.
Textured walls: If your walls have a heavy texture, you might need a thicker, more robust wallpaper type like vinyl. This doesn’t directly affect yardage but is an important consideration for adhesion and finish.
Around outlets and switches: Plan to cut ‘X’ shapes and fold the paper back. This requires careful precision and can lead to small amounts of waste per opening.
Accurate measurement is the foundation of a successful wallpaper project. By following these steps and understanding the nuances of roll coverage and pattern repeats, you can confidently determine the exact wall size wallpaper you need and achieve a professional-looking finish.
