How To Calculate How Much Wallpaper I Need

How To Calculate How Much Wallpaper I Need

How To Calculate How Much Wallpaper I Need

Introduction to Wallpaper Calculation

Wallpaper has been one of the finest ways to elevate the visual appeal of a room for centuries. Offering an aesthetic touch to any space, whether it's your living room, bedroom or office, wallpaper range from traditional and classic designs to modern and contemporary ones. However, an important factor to consider before embarking on the task of wallpapering your space is the calculation of the amount of wallpaper needed for the project.

Understanding The Basics of Wallpaper Calculation

Before we take a deep dive into the calculations, you must understand some essential aspects involved in determining the right amount of wallpaper. The width of the wall, the height of the wall, and the pattern repeat of the wallpaper – these are the three most crucial factors that influence wallpaper calculation.

Wall Width and Height

To mark our journey of wallpaper calculation, we start by measuring the width and height of the walls. The width is calculated as the distance from one corner of the wall to the other, while the height is measured from the floor to the ceiling. Note down these measurements as they will help determine how many rolls of wallpaper you will need.

Pattern Repeat

The pattern repeat on a particular wallpaper is the vertical distance between where the pattern is identical again (repeats). It affects how much additional wallpaper is required because it determines how the wallpaper strips should align. A wallpaper roll with a larger pattern repeat may require more wallpaper to match the pattern correctly.

Remember The Door and Window Space

While calculating the required amount of wallpaper, it is crucial not to overlook the door and window space. You should deduct the area of the doors and windows, as they don't need wallpaper. However, it's always a good idea to order a bit extra to have enough material for potential mistakes or future repairs.

Calculating the Number of Wallpaper Rolls Required

Once you have measured the height and width of the walls, and considered the pattern repeat, the next step is to calculate how many rolls of wallpaper you will need. The calculation can be done by dividing the total square footage of the walls by the square footage of one roll of wallpaper. It's advisable to round up your calculation to the next roll to ensure you have enough wallpaper for your project.

Importance of Accurate Wallpaper Calculation

Knowing the right amount of wallpaper needed is vital for a smooth and efficient wallpaper project. It not only saves time and money but also helps avoid needless waste. Overestimating can lead to unnecessary expenditure, while underestimating can lead to delays in work as you may need to order additional rolls, and there's no guarantee that the same batch of design will be available. Hence, accurate calculations are a must for a successful project.

Ready to Start Decorating?

With a clear understanding of wallpaper calculation, you are ready to go ahead with your decoration plans. Trust your measurements, follow the rules of calculation, and embrace the transformative power of wallpaper, adding charm and character to your cherished space.

Understanding Wallpaper Specifications and Measurements

Understanding the specifications and measurements of wallpaper plays a crucial role in determining how much you’ll need for your project. This section will guide you through the key concepts and calculations required.

Wallpaper Roll Dimensions

A standard roll of wallpaper in the U.S measures 27 inches in width and 15 feet in length. However, wallpaper can also come in different sizes. It’s important to check these dimensions before buying the wallpaper rolls as it will significantly impact how many rolls you'll need.

Wallpaper Coverage

Wallpaper coverage refers to the total surface area that one roll can cover. To calculate this, the width should be multiplied by the length of the wallpaper. Taking the standard dimensions, a single roll usually covers around 30 square feet.

Wallpaper Pattern Repeat

The "pattern repeat" of a wallpaper roll refers to the vertical distance between where the pattern is identical again (repeats). The nature of your wallpaper’s pattern can affect the amount of wallpaper you need. Some patterns can be matched at any point along the repeat (Random Match), while others must be aligned with the same point of the previous strip (Straight Match or Drop Match).

Calculating Wall Area

To determine the amount of wallpaper you need, first, you must calculate the total surface area of your walls. This is done by multiplying the width of your wall by its height. Do this for all the walls and then sum up the total.

Subtract Windows and Doors

When calculating your wall area, remember to subtract the square footage of your windows and doors. This will give you a more accurate estimation of the wallpaper required.

Estimating the Number of Rolls Needed

Once you have your wall area, divide this number by the coverage of a single roll. Always round up to the next whole number to account for pattern matching and errors.

Consider Additional Rolls for Mistakes

Finally, it's wise to purchase an additional roll or two. This will cover any errors made during the process or future repairs. Also, trying to buy more wallpaper later can lead to slight color variations due to different printing batches.

How to Measure Your Room Accurately

The key to ordering the correct amount of wallpaper starts with accurate measurement of your room. By taking precise measurements, you'll save yourself both time and money. Here’s a surefire way to do it:

1. Measure Your Wall’s Dimensions

Measure the height and width of each wall you plan to wallpaper. Use a high-quality tape measure for this task. While measuring the height, start from the baseboard to the ceiling. For the width, measure from one corner to the other.

2. Find the Total Wall Area

To find the total area of a wall, simply multiply its height by its width. Repeat this process for each wall and add all the answers together. This creditable estimation gives you an idea of how much wallpaper you need.

3. Account for Windows and Doors

When dealing with areas having doors or windows, their surface area should be subtracted from the total wall area. Measure their width and height, and multiply these dimensions to get the area. Deduct this from your total.

4. Calculate the Repeat Pattern

Wallpapers come with a repeat pattern that can impact the quantity needed. If your chosen wallpaper has a large design, you may need more to match the patterns correctly.

5. Number of Wallpaper Rolls

Most wallpaper rolls cover around 55 square feet. But, this can vary, so make sure to check the manufacturer's information. Divide your total adjusted area by the coverage of a single roll to figure out how many you need.


Always order an extra roll. This ensures you have enough in case a sheet gets damaged, or if you make a mistake. Also, if your room has sloped walls or unique architectural details, you may want to consult a professional for the most accurate measurements.

Accounting for Doors and Windows in Your Calculations

When calculating the wallpaper needed for a room, it's important not to overlook the role doors and windows play in the calculation. You might think that you should keep the total wall area as is since doors and windows make a negligible difference. However, if you want an accurate figure, you need to account for these areas separately.

Calculating Door Area

To calculate the area of a standard door, multiply the standard width, 0.83 meters by the standard height, 2.03 meters which equates to about 1.68 square meters. Note, if your doors are not standard, measure them and use your measurements.

Calculating Window Area

Windows sizes vary greatly, and therefore, to get an accurate measurement, you should measure your window. Multiply the height by the width of the window to get the window area.

Subtracting Door and Window Area from Total Wall Area

After measuring the areas of the doors and windows, subtract these from the total wall area. This ensures you don't buy more wallpaper than necessary, saving money and reducing waste.

Accounting for Excess and Waste

While calculating the area to wallpaper, it is essential to account for excess and potential wastage, which is often the case when cutting wallpaper to fit around doors, windows and corners. It is generally recommended to add an extra 10-15% to your wallpaper order to account for these things. This way, you will make sure you won’t run out of wallpaper in the midst of the project.

Scaling Up Your Calculations

If you're dealing with a large room with several doors and windows, you need to scale up your calculations. Count the number of doors and windows and adjust your totals accordingly. This will ensure you purchase sufficient wallpaper and limit wastage.

Last Minute Tips

Calculating your wallpaper needs involves more than just adding up surface areas. By factoring in elements like windows and doors, as well as potential waste, you can save money, limit wastage, and make sure your DIY project goes as smoothly as possible.

Tips to Calculate Wallpaper Coverage for Complex Room Shapes

Calculating the amount of wallpaper for complex room shapes can seem challenging. However, with some basic math and careful considerations, you can accurately estimate the amount of wallpaper you'll need.

Break Down the Room Into Simple Shapes

Start by breaking down the room into basic geometric shapes like rectangles, squares, and triangles. Measure the height, width, and length of each section separately. By doing this, you'll be able to break down a complex room design into simpler shapes that are easier to calculate.

Use a Formula for Each Shape

Once you've broken down the room into simpler shapes, use the appropriate formula to calculate the area for each one. For instance, for rectangles and squares, multiply the width by the height. For triangles, multiply the base by the height and then divide by two. This will give you the exact area of each segment.


Rectangle's area = Height x Width  
Triangle's area  = 1/2 x (base x height)

Consider Door and Window Areas

Doors and windows typically do not require wallpaper. Hence, you need to subtract their areas from your overall calculation. Measure these areas separately, and keep track of the total square footage that will not be papered.

Adjust for Pattern Repeat

If you have chosen a wallpaper design with a pattern repeat, you might need more wallpaper than your area calculation to ensure the patterns align. Factor in the drop repeat pattern into your calculations. This may require professional help if you're unfamiliar with the process.

Calculate for Additional Runs

Sometimes, you may need to add extra runs, or vertical strips of wallpaper, to cater for any offcuts or mistakes. A safe bet is to add an extra 10-15% to your total wallpaper calculation. This helps ensure that you have a sufficient amount of wallpaper to complete the task efficiently.

Order Extras

Lastly, remember to order a little extra than your estimation. It can be frustrating to run out of wallpaper during the project, and colour batches can vary between orders. Ordering a little extra ensures a match and accounts for future repairs.

Do A Recap

Once you're done with your calculations, do a quick recalibration. Ensure all your measurements are correct, your calculations are accurate, and your extrapolation for wastage is sizable.

This way, you'll navigate the tricky task of estimating the right amount of wallpaper for complex room shapes. With these fundamental steps, your project becomes manageable, precise and more satisfying.

Calculating Repeat Pattern Wallpapers

When choosing a wallpaper with a repeat pattern, you can't just rely on the dimensions of the room to determine how many rolls you need. The pattern's repeat also affects the amount of wallpaper needed. The repeat is the vertical distance between where the pattern is identical again (repeats).

Understanding Wallpaper Pattern Repeat

Wallpaper patterns fall under three categories: random pattern match, straight pattern match, and drop pattern match. Random pattern matches have no specific design repeat and can align anywhere. You will find this mostly on textures or natural surfaces, like wood or stone.

Straight match wallpapers repeat the pattern at the ceiling line. All elements of the design align horizontally with the previous strip. Straight match papers, therefore, do not waste much paper.

Drop match wallpapers have every other strip identical. These are the most complicated to hang because every other strip will be cut differently and generate more waste.

Calculating Wallpaper for Repeat Patterns

To calculate how much wallpaper you need for a repeat pattern, you will need to understand the repeat measurement. This can be found on the product label. Divide the repeat measurement by the length of your wallpaper roll. This will tell you how many repeats you can get out of one roll. Then, count how many repeats you will roughly need to cover your wall height. This calculation will give you the number of rolls you need.

Additional Considerations

While calculating, remember to account for features like windows and doors, and add an allowance for waste due to pattern matching, trimming, and mistakes. It is always better to overestimate rather than underestimate your requirements, so consider purchasing an additional roll for unforeseen issues.

A Practical Example

Suppose you're selecting a wallpaper with a pattern repeat of 25cm on a roll that measures 10m. Each roll will provide 40 repeats (1000cm ÷ 25cm). If your wall height is 2.5m, you'll need 10 repeats per vertical strip (250cm ÷ 25cm). You can get 4 vertical strips out of one roll (40 repeats ÷ 10 repeats per strip), so you'll divide the total number of strips you need by four to find out how many rolls you need to purchase.

Also, remember to consider the width of your wallpaper and the width of your wall. This will affect the number of strips you need.

How to Save on Wallpaper: Common Mistakes to Avoid

In the endeavor to purchase and install wallpaper, there are common pitfalls that can lead to unnecessary waste or expense. By being aware and taking precaution against these common mistakes, one can save on the total cost of wallpaper and avoid dissatisfaction with the result. Let's discuss these mistakes in detail.

Underestimating the Quantity Required

One common mistake that several people make is not estimating the right quantity of wallpaper required. Not purchasing enough wallpaper may lead to discontinuation in the pattern or design, causing aesthetic disruption and forcing you to order more. Using a wallpaper calculator and carefully considering factors like pattern repeats can aid in making an accurate estimate. Always consider ordering a bit extra as a contingency for any unforeseen incidents or calculations error.

Purchasing Cheap Quality Wallpaper

While it may be tempting to opt for the cheapest options available, it's crucial to consider the quality of the wallpaper. Low-cost wallpapers may peel off, fade, or tear easily, requiring frequent replacements and additional expense. Always opt for premium quality material that boasts durability and excellent finish. Even if the initial cost is high, it can represent real savings over time.

Not Preparing the Wall Surface

Before installing wallpaper, the wall surface must be properly prepared. Skipping this stage might lead to uneven surfaces, causing bubbles and poor adhesion of wallpaper. Hence, sanding the walls, removing any residues, and applying a primer are all essential steps in creating a smooth and ready-to-use surface. This preparation enhances the longevity and look of the wallpaper.

Ignoring Directions for Application

Each wallpaper comes with specific application instructions based on its material and design. Ignoring these directions can result in improper application, leading to wastage of wallpaper and impacting the overall look. Therefore, make sure to follow the manufacturer's instructions

Not Considering Room Conditions

Every room in a house has different conditions: moisture, sunlight, wear and tear, etc. Choosing the same kind of wallpaper for all rooms without considering the specific needs of each space is a common mistake. Wallpapers vary vastly in terms of water resistance, lightfastness and durability, and choosing one that suits the conditions of a space extends its lifespan and ultimately saves money.

Failing to Hire a Professional Installer

While doing it yourself might seem like a cost-saving measure, wallpaper installation is a skillful job. One slight mistake could cost you more in terms of material waste and future repairs. Hiring a professional installer can ensure a smooth and seamless finish, reducing wastage and mishaps. This, in turn, can translate into significant savings in the long term.

Final Check-List for Accurate Wallpaper Calculations

Having the right amount of wallpaper is key to achieving the look and effect you envision for your room. Below is a final checklist to ensure accurate wallpaper calculations.

Determine the Wall Area

To begin, accurately measure the width and height of each wall in feet. This can be done using a tape measure or a laser measuring tool for even more accuracy. Multiply the width and height of each wall to determine the square footage. Add up the total square footage of all the walls to get the overall area.

Don't Forget Doorways and Windows

Subtract the area of any doorways and windows from the total wall area. This ensures you aren’t buying and cutting unnecessary amounts of wallpaper.

Calculate the number of Wallpaper Rolls Needed

Knowing the area of the wallpaper roll is vital - usually given in square feet. Divide the total wall area by the area of one roll of wallpaper to get the total number of rolls needed. Be sure to round up to the nearest whole roll.

Consider Pattern Repeat

If your chosen wallpaper has a large pattern repeat, you may need more wallpaper to match the pattern across the wall. Make sure to factor this in when calculating the number of rolls needed.

Make room for Mistakes

When it comes to wallpapering, mistakes are bound to happen, especially for novices. So, always add an extra roll to your total — think of this as your insurance policy.

These steps outlined above will give you a precise estimate of how much wallpaper you will require for your room, eliminating unnecessary wastage and extra expenses.