Buying too much wallpaper means wasted money and storage headaches. Buying too little means an incomplete project and the hassle of reordering, hoping the dye lot matches.
Accurately calculating how much wallpaper you need is critical. Standard rolls vary in size, and so do repeat patterns. Here’s how to get it right.
how to measure your walls for wallpaper
Before you touch a calculator, you need precise measurements. Grab a tape measure and a notepad. You’ll be measuring the width and height of each wall you plan to cover.
Measure the height: Start at the ceiling or crown molding and measure down to the baseboard. Record this number in inches. Do this for each wall, as heights can vary slightly.
Measure the width: Measure the widest part of each wall. Again, record this in inches. If you have windows or doors, measure the wall space between them and to the edges of their openings. You’ll subtract these areas later, but it’s good to have the full wall measurement first.
calculating the total square footage of your walls
Once you have your measurements, calculate the square footage for each wall and sum them up. For each wall:
Wall Square Footage = Wall Height (in) Ă— Wall Width (in)
Add the square footage of all your walls together to get the total square footage you need to cover. For example, if you have four walls measuring 96 inches high and 120 inches wide each, the calculation would be:
96 inches Ă— 120 inches = 11,520 square inches per wall
11,520 square inches/wall Ă— 4 walls = 46,080 total square inches
Convert this to square feet:
46,080 square inches / 144 square inches/sq ft = 320 sq ft
understanding standard wallpaper roll sizes
Wallpaper comes in different sizes depending on the manufacturer and country of origin. In the US, the most common size for a double roll (which is what most calculators assume) is approximately 20.5 inches wide by 33 feet long. This yields about 56.4 sq ft per double roll.
However, some manufacturers sell single rolls, which are half the size of a double roll (roughly 20.5 inches wide by 16.5 feet long, or 28.2 sq ft). Always check the dimensions on the wallpaper packaging or product description. If your wallpaper is sold in single rolls, you’ll need twice as many.
the impact of pattern repeat
This is where things get tricky and where many DIYers make mistakes. The pattern repeat (or pattern match) is the vertical distance on the wallpaper where the pattern starts to repeat. It’s crucial because you lose a portion of your wallpaper roll for each strip to ensure the pattern aligns from one strip to the next.
No repeat: For solid colors or very subtle textures, you might not need to worry about pattern repeat. This is rare for decorative wallpapers.
Straight match: The pattern aligns on adjacent strips. The repeat is usually stated in inches (e.g., 18 inches, 21 inches). You’ll lose a portion of the roll equal to the pattern repeat.
Drop match: The pattern on adjacent strips is offset. This requires more paper because you need to cut the second strip to match a different point on the roll. Drop matches are often half the pattern repeat (e.g., if the repeat is 21 inches, the drop match might be 10.5 inches). Check the wallpaper specifications; some require you to cut matching sections from a higher point on the roll.
How to account for pattern repeat:
- Find the pattern repeat measurement (in inches) on your wallpaper’s packaging or product details.
- If it’s a drop match, divide the repeat by two.
- Add this number to your wall height measurement before calculating how many strips you can get from a roll.
For example, if your wall height is 96 inches and your pattern repeat is 21 inches:
Adjusted Height = 96 inches + 21 inches = 117 inches
how to calculate wallpaper strips per roll
Now, let’s figure out how many full-height strips you can get from a single roll. This calculation assumes you are using a standard double roll (33 feet or 396 inches long).
Number of Strips per Roll = Roll Length (in) / Adjusted Wall Height (in)
Using our example with an adjusted height of 117 inches:
Number of Strips per Roll = 396 inches / 117 inches = 3.38
You can only get whole strips, so you round down. In this case, you get 3 full strips from one double roll.
calculating the total number of rolls needed
Now you need to know how many strips you’ll need in total for your project.
Total Strips Needed = Total Wall Width (in) / Wallpaper Width (in)
Let’s say your total wall width is 480 inches (four walls, each 120 inches wide).
Total Strips Needed = 480 inches / 20.5 inches (standard wallpaper width) = 23.41
Again, round up to the nearest whole number: you need 24 strips.
Finally, divide the total strips needed by the number of strips you can get per roll:
Total Double Rolls = Total Strips Needed / Strips per Roll
Total Double Rolls = 24 strips / 3 strips/roll = 8 double rolls
using a wallpaper calculator
Doing these calculations manually can be time-consuming and prone to error. Thankfully, most wallpaper retailers and many DIY websites offer free online wallpaper calculators. These tools simplify the process significantly.
Typically, you’ll input:
- The height of your walls
- The width of your walls (or you can input individual wall dimensions)
- The width of the wallpaper roll
- The pattern repeat (if applicable)
- Whether the roll is a single or double roll
The calculator then does the math for you, providing an estimated number of rolls required. Some calculators also factor in waste for cuts around windows and doors.
You can use a tool like the wallpaper installation cost calculator to estimate not just materials but also labor, though it’s always best to double-check the roll count yourself or consult with your installer.
tips for ordering and what to watch out for
Always order extra: It’s a good practice to order at least one extra roll beyond what your calculation suggests. This accounts for any mistakes during installation, future repairs, or if you decide to wallpaper another small area later. It also ensures you have backup in case of damage during shipping.
Check the dye lot: Wallpaper is produced in batches called dye lots. Rolls from different dye lots can have slight color variations. Always ensure all the rolls you purchase for a project come from the same dye lot. This information is usually printed on the wallpaper label.
Consider the type of wallpaper: While this guide focuses on standard paper, materials like easy peel and stick wallpaper might have slightly different coverage, especially if the design is intricate. Always check manufacturer recommendations.
Don’t forget waste: This calculation aims to minimize waste, but you will always have some. Cuts around windows, doors, electrical outlets, and uneven ceilings or floors contribute to waste. Professional installers often add 10-20% for waste and matching.
Measure twice, cut once: This old adage is especially true for wallpaper. Double-check all your measurements before ordering. A small error can lead to ordering too much or too little.
Pattern continuity: For visually impactful designs like those found in Yellowstone wallpaper designs or floral patterns like those from Rifle Paper Co. wallpaper, the pattern repeat is paramount. Taking the time to understand and calculate for it will save you frustration and ensure a professional-looking finish.
