Wallpaper Calculator – Rolls, Coverage, Pattern Repeat, Waste And Cost
The Wallpaper Calculator on MyTimeCalculator is built for homeowners, decorators and interior designers who want a practical way to estimate how many rolls of wallpaper a project will require. It brings together single wall, multi-wall room and perimeter-based calculations with pattern repeats, waste and cost in one interface.
Instead of guessing, you can enter real wall sizes, door and window openings, wallpaper roll dimensions and pattern match information. The calculator then transforms everything into rolls, coverage and a realistic allowance for waste and trimming.
1. Basic Wallpaper Coverage Formula
At its core, wallpaper coverage is based on wall area and roll area. Wall area Awall is calculated as
and the nominal coverage from one roll, ignoring pattern repeat and trimming, is
If there were no pattern to match and no waste, the minimum number of rolls would simply be Awall / Aroll. In practice, pattern repeats and trimming reduce the usable area per roll, so the actual rolls needed is higher.
2. Pattern Repeat, Drop Length And Usable Strips
Most wallpapers have a vertical pattern repeat. When you hang strips side by side, the pattern has to line up, which means each strip must be cut to a length that fits an integer number of repeats plus a small trimming allowance at the top and bottom. The calculator models this by using an effective strip length
For no repeat, random match or very small repeat, the trim allowance is relatively small. For straight match, half-drop and quarter-drop patterns, the effective strip length uses the repeat value to align motifs correctly. The number of full strips from one roll is then
Combined with roll width, this determines how many wall widths each roll can cover.
3. Single Wall Versus Full Room Calculations
The single wall tab focuses on one wall, which is especially useful for feature walls behind beds, sofas or TV units. You enter wall width, wall height, roll width, roll length and pattern details. The calculator reports
- Total wall area in square meters and square feet
- Effective coverage per roll after pattern repeat and waste
- Rolls required, rounded up to a whole number
- Notes about pattern type and how aggressive the waste allowance is
The multi-wall tab generalizes this to a typical rectangular room by summing the widths of four walls. It then subtracts the area of doors and windows based on their dimensions and counts. This gives a net wallpaper area that reflects real surfaces rather than raw perimeter.
4. Doors, Windows And Openings
Doors and windows do not normally need full wallpaper coverage, so their areas are subtracted from the wall area. Given width, height and count, each opening contributes
The calculator subtracts the sum of all door and window areas from the total wall area. To stay conservative, many installers still keep a small portion of this as waste, which is why an overall waste percentage can be applied on top of the geometric subtraction.
5. Room Perimeter, Openings And Cost
Sometimes you know the room perimeter more easily than individual wall widths. The perimeter tab starts from
and lets you subtract a total openings area entered in either square meters or square feet. It then uses the same roll size, pattern and waste settings from the single wall tab to estimate the number of rolls.
Once rolls are known, the cost estimate is straightforward:
This does not include labor, adhesives or tools, but gives a quick material budget you can compare across designs.
6. Professional Pattern Match Types
The pattern system in this calculator reflects common wallpaper specifications:
- No repeat or random match, where pattern alignment is flexible.
- Straight match, where motifs align horizontally from strip to strip.
- Half-drop match, where each successive strip shifts vertically by half a repeat.
- Quarter-drop match, with a vertical shift of a quarter repeat.
- Custom repeat length for unusual designs or murals.
All of these are handled through the effective strip length logic so that more complex patterns naturally consume more wallpaper per square meter of wall area. This is why two papers with the same roll size can require different numbers of rolls on the same wall.
7. Practical Steps For Using The Wallpaper Calculator
- Read the wallpaper label to confirm roll width, roll length, pattern match type and pattern repeat length.
- Measure your wall or room. Decide if you want to use single wall dimensions, four walls or total perimeter.
- Enter wall sizes, height and units in the relevant tab, and include doors and windows where appropriate.
- Enter roll dimensions and pattern details in the single wall tab so all other tabs can reuse them.
- Choose a waste percentage that fits your comfort level and the complexity of the room.
- Add a realistic price per roll in the perimeter tab if you want a material cost estimate.
- Generate the summary and review rolls, coverage and cost before placing your wallpaper order.
It is usually wise to add at least one extra roll beyond the theoretical minimum, especially for patterned wallpapers, awkward rooms or future repairs. The calculator gives a solid baseline, and the extra roll is your insurance policy.
Wallpaper Calculator FAQs
Frequently Asked Questions
Common questions about wallpaper rolls, coverage, pattern repeats, waste and cost when using this Wallpaper Calculator.
Each strip must be cut so that the pattern lines up with the strip next to it. That means you cannot use every centimeter of roll length. Some length is lost in matching repeats and trimming the top and bottom. The larger the repeat, the more material is lost per strip, which reduces the effective coverage of a roll. This calculator builds that effect into its strip-length and coverage calculations.
For plain or very small pattern repeats in simple rooms, 10 percent waste is often enough. For busy patterns, irregular walls, sloped ceilings or many openings, 15–20 percent is more realistic. The waste setting in this calculator is meant as a flexible cushion; you can increase it if you prefer additional safety or plan to keep spare rolls for future repairs.
In theory you can subtract their full area, since you do not wallpaper the entire opening. In practice, some of that area still becomes waste because you cut wallpaper around frames and trims. The calculator subtracts the geometric area you specify and then applies a global waste percentage to reflect this. Many professionals subtract openings but still keep a modest waste allowance to avoid ordering too little wallpaper.
Different calculators and shops use slightly different safety margins for pattern repeats, trimming and tricky areas. Some may round up more aggressively or assume extra hidden surfaces like returns and alcoves. The numbers from this tool should be treated as a well-informed estimate. For expensive designs or complicated rooms, it is sensible to compare with your supplier’s recommendation and consider ordering one extra roll as a backup.
You can still use the area and coverage logic to understand how big a mural needs to be, but murals are often supplied as custom panels rather than standard rolls. For murals, the main output you want is total wall area and dimensions. Use that from the calculator, then follow the mural supplier’s panel layout and overlap instructions rather than the roll-based strip count used here for traditional wallpaper.