Wallpaper is sold by the roll, but you hang it in full-height strips called drops — and matching a pattern wastes some of each roll. This tool does that maths: enter the total wall length, ceiling height, your roll’s width and length, and the pattern repeat, and it tells you how many rolls to buy. It runs entirely on your device.
Enter a value.
Enter your room and roll dimensions to see how many rolls you need.
An estimate for planning. Buy a spare roll from the same batch, and remember dye lots can differ between later purchases.
How it works
First it finds how many drops you can cut from one roll: the roll length divided by one drop, where a drop is the ceiling height plus one pattern repeat for matching. That division is rounded down, because a part-drop left on the roll is usually unusable. Then it counts the drops needed around the room — the total wall length divided by the roll width, rounded up.
Dividing drops needed by drops per roll (rounded up) gives the number of rolls. A larger pattern repeat means each drop is longer, so fewer fit per roll and you need more rolls — which is why patterned papers cost more to hang. Leave the repeat at zero for plain or free-match papers.
Practical examples
A plain-paper bedroom
20 m of wall, 2.5 m high, standard 0.53 × 10 m rolls, no repeat: 4 drops per roll and 38 drops needed, so 10 rolls.
Adding a pattern repeat
Same room but a 32 cm repeat pushes each drop to 2.82 m, so only 3 drops fit per roll — now you need 13 rolls. The extra three rolls are the cost of pattern matching.
Tall feature wall
For a 3.2 m high wall with 10 m rolls you still get 3 drops per roll; the calculator flags it if a room is so tall that not even one drop fits, so you know to buy longer rolls.
Frequently asked questions
What do I enter for wall length?
Measure around the room along the skirting — the total length of all walls you’re papering (the perimeter). You can subtract very large openings, but many decorators leave standard doors and windows in as built-in waste allowance.
What is a pattern repeat?
The vertical distance after which the design repeats. To line the pattern up between neighbouring strips you often waste up to one repeat per drop, so a bigger repeat means more waste. It’s printed on the roll label.
What roll size should I use?
The defaults — 0.53 m wide, 10 m long — are the European standard. Check your roll label, as widths of 0.53 m and 0.70 m and lengths of 10 m are all common, and enter the actual figures.
Why round drops per roll down but rolls up?
A leftover part-drop on a roll usually can’t be used on a full-height wall, so it doesn’t count — hence rounding down. But you must have enough total rolls, so the final roll count rounds up. Together they keep you from running short.
Does it account for doors and windows?
Not automatically. Offcuts above and below openings often cover the small areas around them, so leaving openings in the wall length acts as a safety margin. Only subtract genuinely large openings like patio doors.
Should I buy a spare roll?
It’s wise. Buying one extra from the same batch guards against damage, future repairs and mis-cuts — and dye lots vary, so matching a roll later can be hard.
Does this work for a feature wall only?
Yes — enter just that wall’s width as the length. The drop maths is identical; you’ll simply get a smaller roll count.
What about ceilings or non-standard heights?
The tool assumes straight, full-height walls. For sloped ceilings, stairwells or papering a ceiling, calculate each section separately and add the rolls, allowing extra for the awkward cuts.
Is anything I enter stored?
No. Everything is calculated locally in your browser; nothing is uploaded and analytics never sees your measurements.
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