How Much Wallpaper Do You Need A Wall Measurement Guide

Measuring is the step you should never hurry through

Wallpaper can be great… but it can only be that if you buy the right amount. If you buy less than needed, soon you will have to look for a matching roll (which is never a pleasant experience). Overlapping the rolls of wallpaper will be the case of the paper you have paid for but will never use.

Precise measuring is the main reason for the smoothness of your project, especially when you have to deal with areas like windows, doors, odd corners, or a pattern that requires lining up. In this guide, I'm going to reveal the method of measuring walls for wallpaper that actually works in ordinary homes (where walls are hardly perfect).

What you need before you start

Keep it simple:

• Tape measure (or a laser measure if available)
• A notebook/phone notes
• Calculator
• Step stool for higher walls

Quick tip: Choose one unit system and stay with it. Feet/inches or meters/cm, any of them is okay. Just don't mix them halfway through.

Step-by-step: Measuring Walls for Wallpaper (the Practical Way)

Step 1: Measure the wall height (and don't rely on just one measurement)

Take a measurement from the base of the wall (where the baseboard sits) to the ceiling.

Perform the exact measurement in 2 or 3 spots on the wall (left corner, middle, right corner). The reason is that floors and ceilings can be unevenly sloped, and you might discover that only after the wallpaper has been applied to the wall.

• Make a note of the highest height among the three measurements.
• Also, consider a bit extra for trimming off later (more on this later)

This is a very common mistake in wallpaper measurements that people do not take into account, and it is exactly when they run out of wallpaper that they notice this mistake.

Step 2: Measure the width of each wall (separately)

Measure each wall from corner to corner.

Even if the room looks symmetrical, measure every wall anyway. Older homes, especially, can be "close enough" visually but not on paper.

• Wall 1: 12 ft
• Wall 2: 10 ft
• Wall 3: 12 ft
• Wall 4: 10 ft

The above measurements are the basis for taking accurate measurements of walls for wallpaper.

Step 3: Find out what to do with the windows and the doors

This is the point where many people get confused. Here is the truth:

Option A (suggested for DIY): Do not deduct doors/windows

The majority of DIYers prefer this method for the following reasons:

• Paper is still going to be wasted when cutting around frames
• You will need some more for errors and matching patterns
• It is easier if you start with wallpapers

Typically, this way corresponds quite nicely with how a wallpaper roll calculator figures it out.

Option B (more precise): Subtract large openings

In case you are sure and would like to cut down on overage:

• Each door/window should be measured width × height
• Then subtract that area (or modify your strip count)

My guideline: I only subtract very large openings (e.g., large sliding doors). For standard windows and doors, I don't do that, mainly because the savings are rarely as much as you think.

This also applies to wallpaper coverage: the greater the number of cut-outs, the smaller the quantity of "usable" leftover scraps.

The method that truly works: count strips (drops), not only to calculate square footage

Numerous guides suggest measuring the entire wall area and then dividing by the coverage of the roll. This way can provide quick estimates; however, it is not very effective when:

• Your walls are high
• The wallpaper has a pattern repeat
• You need to match patterns

Instead, the strip method, which is the most reliable, should be used, and this is basically what a good wallpaper measuring guide would tell you.

Step 4: Determine the length of your "drop" cut

The drop length is equal to the height of the wall plus the trimming allowance.

Furthermore,

• You need to add 2 to 4 inches (5 to 10 cm) as extra at the top and bottom.

Thus, if the wall height is 8 feet, the usual cutting for each strip will be approximately. 8.5 feet.

In case of wallpapers with a pattern repeat, the drop length may be increased since it may be necessary to shift the pattern to make it coincide. This is the reason why a roll of wallpaper is often required for patterned ones.

(In case you are asking how to determine the amount of wallpaper with pattern repeat, the easiest method is: always round your cutting length up to so that the pattern can be aligned.)

Measuring special wall types (real-world situations)

Standard walls

Nothing fancy here:

• Height (use the tallest measurement)
• Width
• Repeat for each wall

Walls with alcoves or chimney breasts

Treat them as separate walls:

• Back section width
• Left return depth
• Right return depth

You'll thank yourself later when you're cutting strips and things actually fit.

Sloped ceilings or stair walls

Use:

• The maximum height at which the wallpaper will reach
• Width of the wall

Plan for more because you will cut off more and throw away more with angled cuts. That's the reason why people look for ways to take measurements of sloped walls for wallpaper, as it is pretty easy to make an underestimation.

Common mistakes (that cause roll shortages)

Here's what trips people up most:

• Measuring height once and assuming it's consistent
• Forgetting the trimming allowance
• Ignoring pattern repeat (big one!)
• Rounding down instead of up
• Not accounting for weird areas (returns, alcoves, boxed-in sections)

In case you are considering how many wallpaper rolls are necessary, there is an honest answer: asufficient number so that you can round it up and not be afraid of running out in the middle of the project.

Calculation example (with real numbers)

Let's use a simple room.

Room:

• Two walls are 12 ft wide
• Two walls are 10 ft wide
• Total width = 12 + 10 + 12 + 10 = 44 ft

Wall height:

• Tallest measured height = 8 ft
• Add trimming allowance = about 0.5 ft
• So drop length = 8.5 ft

Wallpaper roll:

• Width = 20.5 inches (about 1.71 ft)
• Length = 33 ft
• No pattern repeat (solid/random)

Step 1: How many strips do you need?

Total strips = total wall width ÷ roll width = 44 ÷ 1.71 

 25.73 → round up → 26 strips

Step 2: How many strips come from one roll?

Strips per roll = roll length ÷ drop length = 33 ÷ 8.5

= 3.88 → round down → 3 strips per roll

Step 3: How many rolls?

Rolls = strips ÷ strips per roll

= 26 ÷ 3 = 8.67 → round up → 9 rolls

✅ Final answer: 9 rolls

In case of a discernible repetition, one more roll is likely necessary (and, in some cases, even more, depending on the size of the repetition and the height of your wall).

Conclusion: the straightforward practice that facilitates wallpapering

If you only remember this to do it: measure height at different points, take the highest measurement, and calculate it by strips, not only by square meters. This is the most reliable method to measure walls for wallpaper, so you do not run out of it, particularly with patterns and irregular walls.

When you do it for the first time, you will know it is not difficult; it just requires some focus.