Free Wallpaper Quantity calculator with clear step-by-step results.
Wallpaper is counted in drops, not in square metres. Divide the perimeter by the roll width to get the number of vertical drops, then work out how many whole drops a roll yields once the cut length includes trim and pattern matching. Because only whole drops are usable, a 10 m roll giving two 2.7 m drops wastes far more than the arithmetic suggests — which is exactly why the drop-based method is the trade standard.
Drops and cut length
Drops = ceil(perimeter ÷ roll width); cut length = wall height + pattern repeat
Rolls
Rolls = ceil(drops ÷ floor(roll length ÷ cut length))
Roll dimensions, repeat and recommended overlap vary by product. Check the label and buy all rolls from one batch before starting.
Each drop has to start at the same point in the design, so up to one full repeat is trimmed off every length. A 64 cm repeat on a 2.4 m wall can cut a roll from four usable drops down to three.
Only large openings such as patio doors or a full wall of glazing. Standard doors and windows are normally left in, because the paper around them still needs pattern-matched drops and the offcuts rarely reach far.
One, from the same batch. Batch numbers differ in shade, and a single damaged drop later is much cheaper to fix from a matching spare roll than by repapering the wall.