Wallpaper can bring personality, texture, and style to a room in a way that paint simply cannot. However, hanging wallpaper is a precise job, and calculating the correct amount of material is a step that often trips up even seasoned DIYers. Unlike paint, you can't just calculate the total square footage. You must account for the "pattern repeat," which can create a significant amount of waste. Our Wallpaper Calculator is specifically designed for this challenge. It helps you accurately estimate the number of rolls you need by factoring in your wall dimensions, roll size, and the crucial pattern repeat, ensuring you purchase enough material to complete your project with a seamless, professional finish.
How to Use the Wallpaper Calculator
Estimating your wallpaper needs is a systematic process:
- Enter Wall Dimensions: Input the "Total Wall Length" you plan to cover (add all walls together) and the "Wall Height."
- Enter Wallpaper Roll Details: From the wallpaper label, input the "Roll Width" and "Roll Length."
- Enter Pattern Repeat: This is the most important step. Find the "Pattern Repeat" length on the wallpaper label and enter it. If your wallpaper has no pattern (like a simple texture), you can enter 0.
- Calculate Rolls Needed: Click the "Calculate Rolls" button to see the total estimated number of rolls required for your project.
The Crucial Factor: Pattern Repeat
Calculating wallpaper needs is not as simple as dividing the total wall area by the area of a single roll. The reason is pattern repeat.
A wallpaper with a pattern (e.g., floral, geometric) has a design that repeats vertically at a specific interval. This interval, the "pattern repeat," is always listed on the wallpaper label. To create a seamless look, you must align the pattern on each new strip of wallpaper with the strip you just hung. This means that with each new strip you cut, you will have to waste a certain amount of paper from the top of the roll to get the pattern to match up perfectly.
The larger the pattern repeat, the more waste you will generate, and the more wallpaper you will need. A random-match or solid-color wallpaper will have zero waste from pattern matching, making it the most efficient option.
How the Calculation Works
Our calculator uses a strip-based method, which is the most accurate way to estimate wallpaper needs:
- Calculate Strips per Roll: First, it determines how many full, usable vertical strips you can get from a single roll. It does this by dividing the total roll length by the length of one strip (which is your wall height plus the pattern repeat distance for matching).
Strips per Roll = Roll Length / (Wall Height + Pattern Repeat) - Calculate Total Strips Needed: Next, it determines the total number of vertical strips you need to cover the entire width of your walls.
Total Strips Needed = Total Wall Length / Roll Width - Calculate Total Rolls: Finally, it divides the total number of strips you need by the number of strips you can get from a single roll, and rounds up to the next whole number.
Total Rolls = Total Strips Needed / Strips per Roll
Tips for a Successful Wallpapering Project
- Always Buy an Extra Roll: Even with a precise calculator, it is an ironclad rule of wallpapering to always buy at least one extra roll. This provides a crucial buffer for any cutting mistakes, damage during installation, or for future repairs. It's often impossible to get an exact color match if you have to buy another roll from a different batch later on.
- Prepare Your Walls: Wallpaper will not hide imperfections; it will highlight them. Your walls must be clean, smooth, and dry. Fill any holes or cracks with spackle and sand them smooth. It's highly recommended to apply a wallpaper-specific primer to seal the wall and make future removal easier.
- "Book" Your Wallpaper: "Booking" is the process of applying paste to a strip of wallpaper and then gently folding it over on itself (paste-to-paste) to rest for a few minutes. This allows the paper to relax and absorb the moisture evenly, preventing bubbles and shrinking on the wall.
Frequently Asked Questions
Should I subtract for doors and windows?
For estimation purposes, most professional installers do not subtract the area of standard doors and windows. The wallpaper that would cover these openings is often used for the small, tricky pieces needed above and below them. Not subtracting provides a natural buffer and simplifies the calculation. This calculator does not subtract these areas.
What is a "drop match" vs. a "straight match"?
These terms describe how the pattern aligns. A "straight match" means the pattern matches horizontally across adjacent strips. A "drop match" or "offset match" means the pattern is staggered, and you must shift the wallpaper strip up or down (usually by half the pattern repeat distance) to align it. A drop match typically creates more waste than a straight match.
What is a "single roll" vs. a "double roll"?
In the United States, wallpaper is often priced by the "single roll" but sold only in "double roll" or "bolt" packaging. A double roll is simply two single rolls combined into one longer continuous roll. This is done to provide more usable length and reduce waste. Our calculator is based on the dimensions of the physical roll you are buying (typically a double roll).