๐งป Wallpaper Calculator
Enter your room's wall perimeter, ceiling height, the combined area of windows and doors, and your wallpaper roll dimensions to calculate how many rolls you'll need. Handy for estimating purchase quantity before a DIY wallpapering project.
How to use
- Enter the wall perimeter (sum of all wall widths, in meters).
- Enter the ceiling height (in meters).
- Enter the combined area of windows and doors you won't be papering over (in square meters).
- Enter your wallpaper roll's width (cm), length (m), and a waste percentage โ the number of rolls needed is calculated automatically.
How the calculation works
This tool calculates how much wallpaper you need in two ways: from the wall area, and from the number of vertical strips you will actually hang. From area Net area = perimeter ร height โ openings Rolls = net area รท (roll width ร roll length) ร (1 + waste %), rounded up From strips (recommended) Strip length = wall height + 10 cm (trimming allowance) Strips needed = perimeter รท roll width, rounded up Strips per roll = roll length รท strip length, rounded down Rolls = strips needed รท strips per roll, rounded up Wallpaper is hung floor to ceiling one strip at a time, and the short piece left at the end of a roll is usually unusable. Calculating from area alone ignores those offcuts and tends to fall short.
Worked example
Perimeter 14 m, height 2.4 m, openings 3 mยฒ, rolls 92 cm wide and 10 m long Strips: 14 รท 0.92 โ 15.2 โ 16 Strip length 2.5 m, so 4 strips per roll Rolls: 16 รท 4 = 4 (40 m in total) With a 2.6 m ceiling Strips are 2.7 m, so only 3 fit per roll โ 16 รท 3 โ 6 rolls (the area method still says 4, two rolls short)
Things to be aware of
- The strip method counts full strips even over windows and doors, so it errs slightly high. Offcuts can sometimes fill the short pieces above and below windows.
- For patterned wallpaper, add the pattern repeat to each strip length to allow for matching.
- In Japan, standard vinyl wallpaper is often sold by the metre, so use the total length as a guide.
FAQ
How do I find the wall perimeter?
It's the sum of the widths of all the walls in the room. For a rectangular room, it's (length + width) ร 2.
What if my wallpaper has a pattern that needs to be matched?
Patterned wallpaper with a repeat typically wastes more material due to pattern matching. Consider increasing the waste percentage to around 15-20%.
What's a typical wallpaper roll size?
European-style wallpaper commonly comes in rolls about 53cm wide, while Japanese-style rolls (as used in the default values here) are commonly 92cm wide and about 10m long per roll.