Wallpaper Calculator
Rolls of wallpaper needed for your wall area, including waste.
Rolls needed
7
incl. 15% waste
Wall area
300 ft²
Per roll
56 ft²
- Rolls for the walls86%
- Waste (15%)14%
Covering 300 ft² takes about 6 rolls, plus 1 extra for the 15% waste allowance.
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How the Wallpaper Calculator works
The GKCalculators Wallpaper Calculator estimates exactly how many rolls of wallpaper you need to cover your walls, automatically accounting for doors, windows, pattern repeats, and a recommended waste allowance. It's ideal for homeowners, interior decorators, and contractors who want to avoid costly shortfalls or over-ordering before a decorating project.
The calculator begins by determining your total gross wall area. You enter the room's perimeter (or individual wall widths) along with the ceiling height, and the tool multiplies these to produce the full surface area in square feet or square meters. It then subtracts the area of any doors and windows you specify, since these surfaces don't require wallpaper coverage. This net wall area is the true canvas you need to cover and forms the foundation of every estimate that follows.
Next, the calculator factors in the roll coverage of the wallpaper you've chosen. Standard US double rolls typically cover around 56–57 square feet usable area, while single rolls cover roughly 28–30 square feet; European rolls are usually sold by the meter and cover a different amount. Because these figures vary significantly by brand and product, the calculator allows you to input the exact roll coverage stated on the manufacturer's label. Dividing your net wall area by the usable coverage per roll gives a raw roll count before any adjustments.
Pattern repeat is one of the most commonly overlooked factors in wallpaper planning, and it can dramatically increase material consumption. When a wallpaper has a large pattern repeat—say 24 inches—each strip must be cut so the pattern aligns at every seam, which means a significant portion of each strip may be wasted. The calculator asks for the vertical pattern repeat length and uses it to recalculate the effective usable length of each strip, reducing the number of full strips you can cut from a single roll and increasing the total rolls required. Straight-match repeats waste less than drop-match (half-drop) repeats, and the tool accounts for both.
Finally, a waste factor—typically 10–15% for simple rooms and up to 20% for rooms with many obstacles or large pattern repeats—is added to the adjusted roll count and the total is always rounded up to the nearest whole roll. This buffer covers miscuts, tears during hanging, and the need for future patches. The calculator also encourages buying all rolls from the same dye lot, since batches can have subtle color variations that become visible on the wall; getting the right number the first time prevents the frustrating scenario of returning for a second batch only to find a mismatched lot.
Formula
Net Wall Area = (Total Wall Area) − (Door & Window Area) Strips per Roll = Floor[(Roll Length) / (Ceiling Height + Pattern Repeat)] Rolls Needed (raw) = Ceiling[Wall Perimeter / Strip Width] / Strips per Roll Final Rolls = Ceiling[Rolls Needed (raw) × (1 + Waste Factor)]
Pro tips
- Buy all rolls from the same batch so colours match exactly.
Key terms
- Pattern Repeat
- — The vertical distance between identical points in a repeating wallpaper design, which determines how much material is lost when aligning strips so the pattern matches at every seam.
- Drop Match (Half-Drop Repeat)
- — A pattern arrangement where each successive strip is offset by half the repeat length, requiring the pattern to match on alternate strips and typically wasting more material than a straight match.
- Usable Roll Coverage
- — The actual square footage or square meters of wall a single roll can cover after accounting for pattern repeat waste and trim, as opposed to the total printed area of the roll.
- Dye Lot
- — A batch of wallpaper rolls printed at the same time with the same ink mixture; rolls from different dye lots can have subtle color differences that are noticeable once hung side by side.
- Waste Factor
- — A percentage added to the calculated roll count to cover inevitable losses from miscuts, tears, pattern matching, and future repair needs, typically ranging from 10% to 20%.
- Strip Width
- — The width of a single wallpaper strip as it comes off the roll, usually 20.5 inches (52 cm) for US products, which determines how many strips are needed to span a given wall width.
