BuildCalcs Wallpaper Calculator
Estimate wallpaper rolls using the room or wall perimeter, ceiling height, roll dimensions and pattern repeat.
How the wallpaper calculator works
The calculator first works out how many full-width drops are needed. It then adjusts the drop length to the next full pattern repeat, calculates how many complete drops fit on one roll and rounds up to whole rolls.
Should I subtract doors and windows?
For a simple ordering estimate, BuildCalcs does not subtract openings. This leaves useful material for pattern matching, trimming and awkward sections around openings. Large areas of glazing or unusual layouts can be calculated separately.
Frequently asked questions
What happens if I enter no pattern repeat?
The calculator uses the wall height as the minimum drop length and determines how many full drops fit on each roll.
Why add a spare roll?
A spare can cover mistakes, damaged lengths and later repairs. Patterned batches can vary, so buying enough from one batch is often useful.
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Why wallpaper is calculated by drops
Wallpaper cannot be estimated reliably from wall area alone because each vertical drop must normally run from top to bottom in one piece. The calculator divides the total wall width or room perimeter by roll width to find the number of drops, then works out how many full drops can be cut from each roll.
Pattern repeat can reduce drops per roll
For patterned wallpaper, each drop may need to be lengthened so the design aligns with the next one. A large repeat can therefore reduce the number of usable drops from a roll even when the wall height is unchanged. Enter the repeat printed on the roll label; for plain or free-match paper, use zero.
Doors, windows and matching batches
The calculator deliberately does not deduct every opening because material above and below openings can be difficult to reuse as complete drops. Very large openings may justify a manual adjustment, but keeping a small surplus is usually practical. Buy rolls from the same batch number where colour consistency matters, and consider the optional extra-roll setting for complicated rooms or future repairs.