Formula
A drop is the wall height plus the trim allowance. With a pattern repeat, the drop is rounded up to a whole number of repeats.
Drops per roll are the roll length divided by the drop, rounded down. Widths are the width of the walls divided by the roll width, rounded up.
Rolls are the widths divided by the drops per roll, rounded up.
Worked example
2.4 m plus 10 cm trim is a 2.50 m drop. A 10.05 m roll gives 4 drops.
14 m of wall at 53 cm is 27 widths, so 6.8 rolls, rounded up to 7.
Assumptions
Doors and windows are not taken off. The paper above and below them usually comes from offcuts, and the extra covers mistakes.
A half-drop match can waste more than a straight match with the same repeat. Buy from one batch and keep a spare roll if the label suggests it.
Ceilings and lining paper are not counted.
Checked
Checked 11 November 2026. Graham & Brown rolls are listed at 10.05 m × 53 cm, with some designs at 52 cm. Bunnings lists wallpaper rolls at 10.05 m × 53 cm. Farrow & Ball’s guidance gives four drops a roll for a stripe, three for a small repeat and two for a large one.