How Much Wallpaper Do I Need?

Contents:

• Why calculating is needed
• Step-by-step: The Strip Method
• Key considerations
• FAQs

Knowing how to calculate wallpaper correctly ensures that you have the correct amount of wallpaper needed for your project. Underestimating the number of wallpaper rolls you need for your project can lead to the following:

• Mismatched batches - Wallpaper is printed in batches. Within each batch, the colours and print intensity can vary. This means that if you don’t have enough wallpaper and buy more, you’re buying from a different batch, which will have a slightly different colour profile. The mismatch can negatively affect the final result.

• Project delays - You will have to wait for the new roll to arrive on site, this can sometimes take weeks, depending on the type of wallpaper you ordered. These delays can prove costly. 

• Stock issues - By the time you return to purchase a new roll, the batch may be out of stock, or discontinued. This can increase your initial budget by having to find a new batch of wallpaper that matches. 

You can use this article as your wallpaper calculator to avoid any of the aforementioned issues happening to you. 

This guide will enable you to answer key questions such as - ‘How much wallpaper do I need?’ and ‘How many rolls of wallpaper do I need?’ with confidence. 

When attempting to figure out how to calculate wallpaper for your project, it’s important to note that simply calculating the surface area of a wall will lead to an incorrect amount being purchased. 

This is why the Strip Method is so highly regarded, as it takes all the necessary elements into account in order to give you a more accurate estimate of how much wallpaper you will need. Using it will improve your efficiency and prevent delays, as you won’t need to pause the project to order more rolls. You’ll also be able to have matching batches and pattern alignment, which will help to ensure that the final result looks exactly as intended. 

It also enables you to only focus on how to dispose of wallpaper paste at the end of the project.

The best example of how to calculate wallpaper is the Strip Method. The formula used to calculate the Strip Method is: 

• Wall Width/Roll Width = Total number of wallpaper strips

• Wall height + 4 inches/10.16 cm of trim = Strip Height

• Total Strips x Strip Height) /Roll length = Total number of rolls needed, rounded up. 

 

The Strip Method does the following:

• Accurate Wastage Calculation: It calculates the length required for each strip by rounding the required height up to the next full Pattern Repeat . This prevents under-ordering, which is the main cause of critical batch mismatches.

• Focuses on Usable Yield: It determines the exact number of usable strips you get from a roll, rather than relying on the gross square metre area, which doesn't reflect cutting loss.

• Minimizes Risk: By precisely combining the dimensions of the wall (Total Strips Needed) with the yield of the paper (Strips Per Roll), it minimises the risk of running short or buying too much.

As a result, it allows you to have an accurate answer to the question - ‘How much wallpaper do I need?’ This ensures you have enough material to complete the job, including the extra pieces often required for detailed work such as wallpaper corners.

 

Step 1: How Many Strips Across?

This part of the formula is important for ensuring that you have the correct amount of wallpaper strips needed to cover an entire wall. 

You are covering the width of the wall by laying down strips of wallpaper, side-by-side.

The Roll Width is the actual amount of wall covered by a single strip.

Therefore, the calculation is Total Strips Needed = Total Wall Width/Wallpaper Roll Width. 

Take an example of a wall being 500cm wide and the wallpaper roll being 62 cm wide. 

500/62=8.065. 

Since there is a decimal point you round up to the nearest whole number so you’ll need 9 full strips to cover the entire wall.

Having this accurate strip count ensures you can properly use all your wallpaper tools without interruption.

 

Step 2: How Long is each Strip?

The required length of each wallpaper strip depends on the wall height and the wallpaper's pattern repeat.

You need to calculate the Working Height and then round it up to account for the pattern.

Here is the formula to determine how long each strip needs to be: Working Height=Wall Height +10cm

Wall Height: The measurement from the skirting board to the ceiling. 

10cm allowance: This is the buffer for trimming the top and the bottom of the strip to ensure a perfect fit. 

You must also adjust for the pattern repeat, to ensure the pattern matches perfectly with the strips next to it. To do this, you need to round up the Working Height to the next full multiple of the pattern repeat. 

Strip Length = Working Height (Rounded Up to Next Multiple of Pattern Repeat)

 

Here is an example of this part of the formula. 

• Wall Height: 250 cm

• Pattern Repeat (from label): 53 cm

1. Calculate Working Height:
   250 cm+ 10 text cm = 260 text cm

2. Adjust for Pattern Repeat:

   • Divide the Working Height by the Pattern Repeat: 260 cm/53 cm = 4.9 cm

   • Round up to 5 full repeats. 

   • Strip Length: 5 x 53cm = 265cm

Each strip must be 265cm long to ensure you can both match the pattern and have enough left to trim. This will help to make it easier to remove wallpaper at a later date if necessary. 

 

Step 3: How Many Rolls?

This step ensures you account for both the width of the wall and the pattern waste. 

Total Length Required = Total Strips Needed x Length Needed Per Strip

• Total Strips Needed: Calculated by dividing the Total Wall Width by the Roll Width, and rounding up. 

• Length Needed Per Strip: Calculated by rounding your Working Height (Wall Height + Trimming Allowance) up to the next full multiple of the Pattern Repeat.

Example:

• You calculated that you need 8 total strips to cover the wall width.

• You calculated that each strip needs to be 265cm long to match the pattern.

Total Length Required = 8 x 265 cm = 2,120 cm or 21.2 m. 

Knowing this total length allows you to confirm how many rolls of wallpaper you need.

Now that you know the total length required, you can divide this by the length of a single roll.

Total Rolls Needed = Total Length Required/Length of One Roll. Standard rolls are usually 10.05 m. 

 

Continuing on from the above example

• Total Length Required: 21.2m

• Roll Length: 10.05 m 

Total Rolls Needed = 21.2 m/ 10.05m = 2.11 rolls. 

However, because you must always round up, you must purchase 3 rolls to cover the wall. This guarantees you have enough material to cover all required strips, manage pattern matching, and handle the extra material needed for detailed cuts, especially around wallpaper corners.

When attempting to answer the question - ‘how much wallpaper do I need?’  It's vital that all the measurements taken are accurate. Any inaccuracies will lead to the number in the formula being incorrect, which will lead to either purchasing too many or too little wallpaper rolls. Measure multiple times before recording the measurement to avoid making this mistake. 

Once you’ve calculated the final number, it’s recommended to add one extra roll for safety. This is even more important for wallpaper with complex patterns, or first-time wallpapering. Unopened rolls from the same batch can often be returned.