Wallpaper Calculator
Find the number of wallpaper rolls for a room, accounting for pattern repeat, trimming and doors.
How to use the Wallpaper Calculator
- Enter the room length and pick its unit.
- Enter the room width and pick its unit.
- Enter the wall height and pick its unit.
- Enter the roll width and pick its unit.
- Enter the roll length and pick its unit – US double roll ≈ 33 ft; European roll ≈ 10 m.
- Enter the pattern repeat and pick its unit.
- Enter the trim allowance per strip and pick its unit.
- Enter the number of doors – Each door deducts a 3 ft width; windows are not deducted.
- Press Calculate. The result updates automatically as you type, and you can switch the result unit at any time.
About the Wallpaper Calculator
In the US, wallpaper is priced by the single roll but usually packaged as double rolls about 20.5 in wide and 33 ft long (about 56 sq ft). European rolls are typically 0.53 m × 10 m. Check the label for the exact size and the pattern repeat, the vertical distance before the design repeats.
Windows aren't deducted because you still paper above and below them, and the offcuts are rarely reusable. Large repeats waste more paper, so allow an extra roll for patterns over about 18 in, and buy all rolls from the same dye lot.
Formula
Strips = ⌈Wall perimeter (less doors) ÷ Roll width⌉
Strip length = Wall height + trim, rounded up to a whole pattern repeat
Strips per roll = ⌊Roll length ÷ Strip length⌋
Rolls = ⌈Strips ÷ Strips per roll⌉
The strip method is more reliable than dividing areas, because the leftover piece at the end of each roll is usually too short to use.
Example calculation
Using the default values:
- Room length = 14 ft
- Room width = 12 ft
- Wall height = 8 ft
- Roll width = 20.5 in
- Roll length = 33 ft
- Pattern repeat = 0 in
- Trim allowance per strip = 4 in
- Number of doors = 1
the calculator returns:
- Rolls needed: 10 rolls
- Strips needed: 29 strips
- Strips per roll: 3 strips
- Cut length per strip: 8′ 4″
- Wall area (less doors): 392 ft²
Frequently asked questions
How many square feet does a roll of wallpaper cover?
A US double roll covers about 56 sq ft and a single roll about 28 sq ft, but usable coverage is often 15–20% less after trimming and pattern matching.
What is a pattern repeat?
The vertical distance between identical points in the design. Each strip must be cut to a multiple of the repeat so the pattern lines up across seams.
How much wallpaper do I need for a 12 × 12 room?
With 8 ft walls, one door and a 20.5 in double roll, you need about 27 strips; at 3 strips per roll that is 9 double rolls.
Last updated: · Category: Construction calculators