Free wallpaper roll calculator with pattern repeat support. Enter total wall width, height, roll size, and pattern repeat to get the exact number of rolls needed, including door/window deductions and a waste buffer.
Built and maintained by Paul Clark, Redmoon Software
Use before ordering wallpaper for a full room, especially with a bold pattern that has a visible repeat — it prevents an expensive mid-job reorder from a different dye lot.
Many wallpaper calculators ignore pattern repeat entirely, quietly underestimating rolls for patterned designs. This one bakes the repeat into the drop math.
With no pattern repeat, each roll yields the maximum number of drops. Buy 7 rolls — and try to buy them all from the same dye lot / batch.
If a pattern repeat is set, each drop is rounded up to the next full repeat length; otherwise the drop equals the wall height exactly.
Drops per roll = roll length ÷ effective drop length, and strips needed = total wall width ÷ roll width, minus any strips saved by large door/window openings.
Rolls needed = (net strips ÷ drops per roll), inflated by your waste buffer percentage and rounded up to a whole roll.
A pattern repeat forces every drop to start at the same point in the design, so each cut strip must be rounded up to the next full repeat length rather than the exact wall height. That shortens how many usable drops you get from each roll, which is why large repeats can noticeably increase the total rolls needed.
Wallpaper color and pattern alignment can shift subtly between production runs, even for the identical SKU. Buying every roll for a room from a single batch avoids visible seams or color banding where a later-purchased roll meets an earlier one.
Add up the width of every wall you're covering, in a continuous loop around the room, without subtracting for corners — corners just mean a strip gets split across two walls, not removed. Enter door and window openings separately in the deduction field instead of subtracting them from the wall width directly.
Input
480" total wall width, 96" wall height, 20.5" roll width, 33 ft roll length, 0" pattern repeat, 0 sq ft deducted, 10% waste.
Output
7 rolls needed.
Effective drop = 96" (no repeat). Drops per roll = floor(396/96) = 4. Strips needed = ceil(480/20.5) = 24. Rolls = ceil((24/4) × 1.10) = ceil(6.6) = 7.
For a plain paper, rolls needed follows from wall area and roll dimensions. For a patterned one it does not, because each drop must start at the right point in the pattern, and the offcut above that point is waste. The longer the repeat, the more waste per drop.
A large repeat can push usable drops per roll from four down to three, which is a 25% increase in rolls for the same wall.
A straight match aligns the pattern at the same height on every drop. A half-drop match offsets alternate drops by half the repeat, which uses the offcut from one drop as the start of the next and wastes less than the repeat length alone suggests — but it makes the arithmetic non-obvious and is easy to get wrong by hand.
Buy every roll from one batch. Batch numbers exist because colour varies measurably between print runs, and a mismatched roll in the middle of a wall is visible under raking light even when it looks identical in the shop.
Getting the roll count right is only half the wallpaper order. The other half is buying from one dye lot, setting a sane waste buffer, and deducting doors and windows without shorting yourself.
How a pattern repeat forces every wallpaper drop to round up to the next full repeat length, cutting usable drops per roll — with a before/after example showing exactly how many more rolls it costs.
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