Wallpaper Calculator
Rolls of wallpaper by the drop method: wall height plus pattern repeat per drop, drops per roll from the label, drops from the perimeter — not area ÷ roll.
How many rolls to buy for a room, from your walls and the roll size and repeat printed on the label, with the drop count that explains it and the naive area figure for comparison.
Example: 14 m of wall at 2.4 m high with a 0.53 × 10.05 m roll and a 0.32 m repeat: 27 drops of 2.72 m, 3 per roll, 9 rolls — where dividing area by roll area would say 7.
Drops,
not square metres.
Why decorators count drops rather than area, what the pattern repeat costs, how openings and trim are handled, and why rolls should come from one batch.
The drop method
A drop is one full-height strip. Its cut length is the wall height plus one pattern repeat (so the next drop can be aligned) plus any trim allowance you add. A roll yields ⌊roll length ÷ drop length⌋ whole drops — the remainder is offcut. The room needs ⌈perimeter ÷ roll width⌉ drops, and rolls are drops needed ÷ drops per roll, rounded up. Every figure comes from the label of the roll you are buying.
Repeat, openings and trim
A large repeat can halve the yield of a roll; free-match papers waste least, and half-drop (offset) patterns can need an extra half repeat per drop — check the label's match type. Subtracting doors and windows is optimistic because the strip above a door is usually a full drop anyway; the page reduces the drop count proportionally and says so. Trim is your allowance for top and bottom cuts; none is assumed.
Area for comparison
The page also shows rolls by simple area ÷ roll coverage. It is nearly always lower than the drop method, and the drop method is the one that reflects cutting real strips.
What the number does not settle
Feature walls, stairwells, sloping ceilings and papering around fireplaces need drops planned by hand. Buy all rolls from the same batch number; colour varies between batches. Inputs stay in your browser; the same four anonymous usage counts as the rest of the site apply.