How to Measure for Wallpaper: Calculating How Much You Need for Your Project
Time to break out the tape measure (and a little basic math)
When measuring for wallpaper, you’ll need to calculate the square footage of the space that will be wallpapered.
To do this, you’ll multiply the length and width of each wall to determine its square footage.
After that, you’ll subtract the square footage of windows, doors, and other areas that won’t be wallpapered.
Based on these figures, you can calculate how many wallpaper rolls to order.
Installing wallpaper is a fun way to freshen up your home, but before you start peeling and sticking, you’ll have to calculate how much wallpaper you need. For that, you’ll need a tape measure, a pen and notebook to write down the measurements, and a calculator to crunch the numbers. Once you’ve grabbed those items, read through this guide to learn how to measure for wallpaper.
How to Measure for Wallpaper
If you’re hanging wallpaper as a DIY project, one of your first tasks will be measuring the wall space. Then, you can crunch the numbers to figure out how many rolls of wallpaper you’ll need. Here’s how to get the measurements.
Measure the Length and Height of Each Wall
The process for calculating a wall’s square footage depends on its shape and layout. For a standard wall:
Use a tape measure to find the length and height of each wall. Round up all measurements to the nearest foot.
Multiply the length and height to get the wall’s square footage.
Repeat this process for every wall you plan to wallpaper.
For a pointed or triangle-shaped wall:
Measure the length of the base.
Measure the height from the base to the top point of the triangle.
Multiply these figures.
Divide the result by two.
For a wall along a staircase:
Divide the wall into separate sections, which will be easier to measure than the entire wall. The first section will be a rectangle just below the ceiling, running horizontally.
Measure the length and height of the rectangular section.
At the bottom of the stairs, you’ll end up with a triangle-shaped section. Use the steps above to calculate its area.
Subtract Non-Wallpapered Areas
If there are windows, doors, or other areas that don’t need wallpaper, calculate the square footage of each one. Then, subtract its square footage from the wall’s square footage.
For example, let’s say your wall is 96 square feet, but it has a door in the middle. A single door is often 21 square feet, so if you subtract that from the total wall square footage, you’d actually only need 75 square feet of wallpaper for that wall.
Calculate the Total Square Footage
When you’re done, add up each wall’s square footage to get the total square footage of the room you’re wallpapering. If you’re hanging wallpaper in multiple rooms, repeat this process for every room. Make sure to keep the square footage calculations separate if you’re ordering different wallpaper for each room.
Determine How Many Wallpaper Rolls to Order
Now, crunch the numbers to figure out how much wallpaper to order. Let’s say you need 400 square feet of wallpaper, and the wallpaper you’ve chosen covers 31 square feet per single roll. To be safe, you should also purchase 10% more than the total square footage to account for waste. In total, you need 440 square feet of wallpaper.
If you divide the amount of wallpaper needed by a roll’s square footage, you’d see that you’d need 14.2 single rolls to cover the room. But single rolls are sold in multiples of two, so you’d round up to 16 single rolls.
What Is the Standard Wallpaper Roll Size?
A single roll of wallpaper covers between 27 and 36 square feet. Lengths and widths vary by manufacturer, but a single roll is often 20.5 inches wide and 16.5 feet long.
Heads up: Many manufacturers price wallpaper by the single roll but package it in double rolls. They might also require you to buy it in multiples of two. So, if you order four single rolls of wallpaper, you’d receive two double rolls. But if you only need three single rolls, you’d have to round up and order four.
Wallpaper Size by Roll Type
Since wallpaper is priced by the single roll but packaged in double rolls, understanding how much wallpaper to order can be confusing. To help, we’ve broken down the most common wallpaper sizes based on the type of roll:
| Type of Roll | Width in Inches | Length in Feet | Coverage Area in Square Feet |
|---|---|---|---|
| Single | 20.5–27 | 13.5–18 | 27–36 |
| Double | 20.5–27 | 27–33 | 56–61 |
Wallpaper Single Roll Dimensions
In most cases, a single roll of wallpaper measures between 20.5 and 27 inches long and 13.5 to 18 feet wide. Depending on the exact dimensions, one of these rolls will cover 27 to 36 square feet.
Again, many companies require you to order single rolls of wallpaper in multiples of two (in other words, double rolls). If so, you should consider the size of the double roll—rather than the single roll—when measuring for wallpaper.
Wallpaper Double Roll Dimensions
Double rolls are the same width as single rolls (20.5 to 27 inches), but they’re twice as long (27 to 33 feet). You’ll get about 56 square feet of coverage from a double roll of wallpaper.
Factors That Influence How Much Wallpaper You Need
Several factors impact the amount of wallpaper you’ll need for your project. Here are the main ones.
Wall Square Footage
The size of your walls is the most important factor in determining how much wallpaper you need. You can use the steps above to calculate your wall square footage.
If you’re having trouble with the measurements, you can always reach out to a wallpaper installer near you instead of doing it yourself.
Windows, Doors, and Other Non-Wallpapered Areas
If your wall has windows, doors, closets, cabinets, or other areas that don’t need wallpaper, it will reduce the amount of wallpaper you order. When calculating how much wallpaper to buy, make sure to subtract the square footage of each of these areas from your room’s total square footage.
Waste
It’s easy to make mistakes when wallpapering—especially if you’ve never done it before. To account for any cutting errors or measuring mishaps, you should order 10% more wallpaper than you actually need.
Once your wallpaper arrives, remove it from its packaging and leave it in the exact room you're installing it in for a minimum of 24 hours. This allows your wallpaper to acclimate to that room's environment, reducing the risk of shrinkage and potentially saving you money by not having to order more.
What to Do If You Don’t Have the Right Amount of Wallpaper
Realizing you’ve run out of wallpaper mid-project isn’t ideal, but you can solve this problem by ordering more. Just be aware that wallpaper is printed in batches, so even if you purchase the same pattern again, the color might be ever so slightly different.
If you end up with too much wallpaper, you can contact your retailer to see if they accept returns. Depending on the company, you may be able to return unopened rolls of wallpaper within a certain amount of time after your purchase.
Can’t return it? There are plenty of creative ways to use extra wallpaper, such as:
Lining shelves and drawers
Framing it as a piece of artwork
Using it as wrapping paper
Alternatively, you can store the wallpaper in case you need to replace sections of it in the future. If so, be sure to keep it in a cool, dry place, away from sunlight and moisture.
Frequently Asked Questions
No, you don’t always have to remove old wallpaper before applying a new layer. However, you should pull off the existing wallpaper if it’s cracked, peeling, or in poor condition. We’d also recommend against putting wallpaper over textured or dark-colored wallpaper because the old layer may be visible through the new one. In addition, if you try to hang new wallpaper over vinyl-coated wallpaper, the adhesive might not stick properly.
You can paint over wallpaper if it’s smooth and in good shape. But if there are bumps or tears in the wallpaper, they’ll likely show through the paint. Similarly, you should avoid painting over textured wallpaper because the ridges and patterns in the paper will be visible. In either of these situations, you should remove the wallpaper before painting.
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