Calculating how much wallpaper you need is the first step to a successful project. A simple wall area calculation isn’t enough when your wallpaper has a pattern. The pattern repeat is crucial because it dictates how much extra material you’ll need to align the design across seams. Get this wrong, and you’ll end up with mismatched patterns or a shortage of paper.
Understanding pattern repeat
Pattern repeat, also known as pattern match or rapport, is the distance between a repeated element in the wallpaper design. It’s usually measured vertically. A smaller repeat means you’ll likely need more rolls because you’ll have more waste trimming to align the pattern. A large repeat might mean fewer cuts, but each cut needs to be precise to match the next panel.
Wallpaper is sold in rolls. The standard US roll size is typically 20.5 inches wide and 33 feet long. However, European rolls are common too, often 21 inches wide and 32.8 feet long. Always check the dimensions of the specific wallpaper you purchase. For example, some luxury wallpapers might come in wider or shorter rolls.
How to measure your walls
To calculate the total wallpaper needed, you first need to determine the square footage of the walls you intend to cover. Measure the width of each wall and add them together to get the total width. Then, measure the height of the walls from the baseboard to the ceiling. Multiply the total width by the height to get the total square footage of your walls.
Example:
- Wall 1: 10 ft wide x 8 ft high
- Wall 2: 12 ft wide x 8 ft high
- Wall 3: 10 ft wide x 8 ft high
- Wall 4: 12 ft wide x 8 ft high
Total width = 10 + 12 + 10 + 12 = 44 ft.
Total square footage = 44 ft x 8 ft = 352 sq ft.
Don’t forget to subtract the area of large windows and doors, as you won’t be wallpapering over them. Measure their dimensions and subtract their square footage from the total. However, for simpler calculations or if you have many small windows and doors, many professionals add a small percentage (5-10%) to account for cuts and waste.
Calculating wallpaper rolls with pattern repeat
This is where pattern repeat comes into play. Most wallpaper manufacturers will state the pattern repeat on the product’s label or specifications. It’s usually in inches.
The formula:
Number of strips needed = (Total wall width in inches) / (Wallpaper roll width in inches)
Let’s use the previous example: 44 ft total width. Since standard wallpaper is 20.5 inches wide, we need to convert feet to inches: 44 ft * 12 inches/ft = 528 inches.
Number of strips = 528 inches / 20.5 inches/roll ≈ 25.75 strips. You’ll need 26 strips.
Now, we need to figure out how many strips you get from a single roll, considering the pattern repeat. This is the most critical part.
How to determine strips per roll:
- Start with the roll length: A standard US roll is 33 ft (396 inches).
- Add the pattern repeat to your desired strip length: Your desired strip length is your wall height plus a little extra for trimming (e.g., 4 inches). So, for an 8 ft wall (96 inches), you might aim for 100-inch strips.
- Calculate: (Roll length) / (Wall height + Pattern repeat + trim allowance) = Number of strips per roll.
Example continued:
- Wall height = 8 ft = 96 inches.
- Pattern repeat = 21 inches (a common size).
- Trim allowance = 4 inches (2 inches top, 2 inches bottom).
- Desired strip length = 96 + 21 + 4 = 121 inches.
- Number of strips per roll = 396 inches / 121 inches ≈ 3.27 strips. You get 3 full strips per roll.
Final calculation:
- Total strips needed = 26 strips.
- Strips per roll = 3 strips.
- Total rolls = 26 strips / 3 strips/roll ≈ 8.67 rolls.
You should round up to 9 rolls. It’s always better to have a little extra than to run short, especially with patterned wallpaper. You might need this extra for mistakes or future repairs. If you’re using a design with a very large pattern repeat, you may get fewer strips per roll, significantly increasing the number of rolls needed.
What is a ‘straight’ vs. ‘random’ match?
Understanding the pattern match type is also important for calculating how much wallpaper you need.
- Straight match: The pattern on one strip aligns directly with the pattern on the next strip. This is the most common type and is what we’ve used in the calculations above. The repeat is usually measured vertically.
- Random match (or drop match): The pattern doesn’t align directly. You might need to shift the next strip up or down to match the design. This often results in more waste, as you might only get two usable strips from a roll instead of three. Some wallpapers are designed with a half-drop match, where every other strip is offset by half the pattern repeat. This still requires careful alignment but can sometimes be more efficient than a full random match. Always check the manufacturer’s recommendation for random match papers.
If your wallpaper has a random match, you might get fewer usable strips per roll. For instance, instead of 3 strips, you might only get 2. In our example, this would mean 26 strips / 2 strips/roll = 13 rolls. This is a significant increase and highlights why checking the match type is crucial.
How to calculate bolts needed
The term ‘bolt’ is often used interchangeably with ‘roll’ in the US, particularly for fabric. However, in wallpaper, ‘roll’ is the standard term. If you encounter ‘bolt’ in the context of wallpaper, it almost always refers to a standard single roll, which is typically half the length of a double roll (the standard size we’ve been using). A double roll is often around 20.5 inches wide x 33 feet long. A single roll (or bolt) would be approximately 20.5 inches x 16.5 feet.
When purchasing, confirm if the product is sold in single or double rolls. Most wallpaper is sold as a double roll, but manufacturers might specify differently. If the packaging states ‘single roll’, you’ll need to double the number of rolls calculated earlier.
Number of bolts* needed
To reiterate, in wallpaper, ‘bolts’ usually refers to single rolls. So, if a product is sold in double rolls (the most common scenario), and your calculation suggests you need 9 double rolls, you would technically need 18 single rolls if they were sold individually. However, most wallpaper suppliers sell in double rolls. When using our calculator or manufacturer guidelines, they typically assume you are buying double rolls. Always clarify with your supplier if you’re unsure whether you’re ordering single or double rolls.
For example, if a calculator tells you need 8 rolls, and these are sold as double rolls, you buy 8 double rolls. If they are sold as single rolls (bolts), you would need 16 bolts. The key is to know how the wallpaper is packaged and sold.
Extra tips for ordering wallpaper
- Order all rolls from the same dye lot: Wallpaper is printed in batches called dye lots. Rolls from different dye lots can have slight color variations. Ensure all rolls you purchase come from the same lot number to guarantee a consistent color throughout your project.
- Consider the installation difficulty: Some patterns, like intricate florals or bold geometrics, require more precise alignment and can lead to more waste. Designs like flowers on wallpaper or complex geometrics might need a larger pattern repeat and more careful handling.
- Peel and stick vs. traditional wallpaper: If you’re looking for an easier DIY experience, consider easy peel and stick wallpaper. While pattern matching is still important, the installation process is generally more forgiving.
- Don’t forget supplies: You’ll need more than just wallpaper. Ensure you have wallpaper paste (if not pre-pasted), a smoothing tool, a sharp utility knife with extra blades, a measuring tape, a level, and possibly a primer.
- Order 10% extra: As a general rule of thumb, it’s wise to order about 10% more wallpaper than your calculation suggests. This accounts for errors during installation, miscalculations, or future repairs. This is especially true for designs like peacock wallpaper designs or other detailed patterns where matching can be tricky.
- Consider room height: For rooms with unusually high ceilings, you might need to adjust your calculations. For example, if your walls are 10 ft high and the standard roll length only yields two strips, you’ll need significantly more wallpaper.
Using a wallpaper calculator that accounts for pattern repeat is essential. While online calculators can be helpful, understanding the underlying principles ensures you make the right purchase. Always double-check your measurements and the wallpaper specifications before ordering. Whether you’re choosing a classic design or something bold like Rifle Paper Co. wallpaper or Yellowstone wallpaper designs, accurate calculation prevents costly mistakes.