Wallpaper Calculator
Calculate exactly how much wallpaper you need for your project
Room Dimensions
Enter your room measurements below. All fields are required.
Enter the length of your room in meters
Enter the width of your room in meters
Enter the height of your room in meters
Wallpaper Details
Standard roll widths are 0.53m or 0.7m
Standard roll lengths are 10m or 15m
Select the pattern repeat of your wallpaper
Your Results
Your wallpaper calculation results will appear here
Wallpapering Tips
- Always buy an extra roll for future repairs – patterns may be discontinued
- Check all rolls are from the same batch number to ensure color consistency
- Prepare walls properly by cleaning, filling holes, and applying primer if needed
- Consider the pattern match when calculating – complex patterns require more wallpaper
- For best results, hire a professional if you’re unsure about the process
The Art of Hanging Paper: Calculating Coverage
Wallpaper installation is less about decoration and more about geometry. Unlike paint, which can be bought in gallons and blended to match, wallpaper is sold in batches or dye lots. If you calculate incorrectly and run one roll short, the new roll you buy may have a slightly different shade, ruining the entire project.
This Wallpaper Calculator is a professional estimation tool. It goes beyond simple square footage by accounting for the Pattern Repeat—the specific distance between recurring design elements—which dictates how much paper is wasted to ensure the pattern aligns perfectly at the seams.
The Mathematical Model: Drops and Matches
To understand how this tool works, you must stop thinking in “Square Meters” and start thinking in “Drops.”
A Drop is a single vertical strip of wallpaper cut from the roll to cover the height of the wall.
- Perimeter Calculation: The total length of all walls ($L_{total} = 2 \times (Length + Width)$).
- Drops Needed: The perimeter divided by the width of the roll ($0.53m$ is standard).$$N_{drops} = \lceil \frac{Perimeter}{Roll Width} \rceil$$
- Roll Capacity: The tool calculates how many full “drops” can be cut from a single roll, accounting for the height of the room plus the pattern repeat waste.
Critical Input Definitions
1. Room Dimensions
Measure the maximum width and length of the floor.
- Height: Measure from the skirting board (baseboard) to the ceiling (or coving/cornice). Do not include the height of the skirting board itself unless you plan to paper over it (which is rare).
2. Roll Width & Length
- Standard Euro/UK Roll: $0.53m$ wide $\times$ $10m$ long.
- American Double Roll: Often $27$ inches ($0.68m$) wide.
- Note: Always check the label. Wide-width vinyls can be $0.7m$ or even $1.06m$.
3. Pattern Repeat (The Silent Killer)
This is the most important variable.
- Free Match (0cm): Random textures or vertical stripes. No waste. You just line up the next strip at the ceiling.
- Straight Match: The pattern starts at the same vertical height on every strip.
- Offset (Drop) Match: The pattern on the next strip drops down by half the repeat height (e.g., a diagonal diamond pattern). This creates the most waste.
How to find it: The label on the roll will explicitly state the repeat (e.g., “64cm offset match”). Enter 0.64 into the calculator.
The “Waste Factor” Logic
The calculator includes an optional 10% Waste Factor. Why is this necessary?
- Trimming: You never cut a drop to the exact wall height. You cut it 5-10cm longer to allow for trimming at the ceiling and floor to account for uneven walls.
- Mistakes: Tearing wet paper or cutting an outlet hole in the wrong place happens to even the best pros.
- Future Repairs: If a section gets damaged by water or a pet, having a spare roll from the original batch is the only way to fix it invisibly.
Dealing with Windows and Doors
A common amateur mistake is to subtract the exact area of windows and doors from the total. Do not do this.
- Reasoning: You cannot stop a wallpaper pattern in mid-air and restart it on the other side of a window. You must hang a full “drop” and then cut the window out of it.
- The Calculator’s Approach: It assumes solid walls. This provides a built-in safety buffer. The scraps cut from window openings can sometimes be used above doors or below sills, but relying on them is risky.
Frequently Asked Questions (FAQ)
Q: Why does the calculator result seem high?
A: It calculates whole rolls. If you need 5.1 rolls to cover the wall, you must buy 6 rolls. You cannot buy 0.1 of a roll. Additionally, a pattern repeat of 64cm means you might throw away half a meter of paper for every single drop just to get the design to line up.
Q: What if I have a feature wall?
A: If you are only papering one wall, enter the length of that single wall into the “Room Length” field and set the “Room Width” to 0.
Q: Can I return unused rolls?
A: Usually, yes, provided the plastic seal is unbroken. It is far safer to buy 8 rolls and return 1 than to buy 6 and desperately try to find a 7th that matches the color batch.
Scientific Reference and Citation
For industry standards on wallcovering estimation and installation:
Source: Painting and Decorating Association (PDA). “Code of Practice for the Application of Wallcoverings.”
Relevance: The PDA sets the professional standards for decorators in the UK and Europe. Their guidelines emphasize the necessity of batch number verification and the calculation methods for pattern repeats to minimize joint visibility.