What this calculator does
Rolls are calculated from strips, not from area. A 5 by 4 metre room with 2.4 metre walls needs 27 strips, and a standard roll yields four at that drop height, so seven rolls plus one for trimming.
Pattern repeat is what changes the answer, sometimes dramatically. With no repeat each strip is cut at exactly 2.4 metres and a 10 metre roll gives four. With a 32 cm repeat, each strip must be cut at 2.56 metres so the pattern lines up, and the roll yields only three. That single change takes the order from seven rolls to nine.
The formula
The wall area less openings is divided by the roll width to give the number of strips needed. The drop height is rounded up to a whole number of pattern repeats, and the roll length divided by that gives usable strips per roll. Dividing strips by strips per roll and rounding up gives the rolls, with a further allowance for trimming.
| Term | Meaning |
|---|---|
| Pattern repeat | The vertical distance before the pattern recurs. Drives waste at the top of each strip. |
| Drop | One cut length of paper, from ceiling to skirting plus trim allowance. |
| Straight match | Pattern lines up at the same height on adjacent strips. |
| Offset or drop match | Pattern is staggered between strips, which wastes more than a straight match. |
The inputs explained
| Field | What to enter |
|---|---|
| Room length (m) | Room length in metres. |
| Room width (m) | Room width in metres. |
| Wall height (m) | Wall height, floor to ceiling. |
| Doors | Doors, deducted at a standard size. |
| Windows | Windows. |
| Roll width (m) | Roll width in metres. European rolls are usually 0.53 m. |
| Roll length (m) | Roll length. Ten metres is standard. |
| Pattern repeat (0 = none) (cm) | Pattern repeat in centimetres. Enter 0 for a plain or random-match paper. |
When to use it
Ordering wallpaper
Rolls must all come from the same batch, so ordering enough first time matters more than with paint.
Comparing patterns
A large repeat can add a third to the order, which changes the real cost of a design.
Budgeting a feature wall
A single wall needs far fewer rolls, and the calculation scales down accordingly.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much does the pattern repeat cost?
The same room with papers of different pattern repeat.
| Pattern repeat | Rolls needed | With 10% extra for trimming | Usable strips per roll |
|---|---|---|---|
| none | 7 | 8 | 4 (drop height 2.40 m) |
| 16 cm | 7 | 8 | 4 (drop height 2.40 m) |
| 32 cm | 9 | 10 | 3 (drop height 2.56 m) |
| 64 cm | 9 | 10 | 3 (drop height 2.56 m) |
Questions
Why does pattern repeat matter so much?
Because every strip must start at the same point in the pattern, so each drop is cut to a whole number of repeats. A 2.4 m wall with a 32 cm repeat needs 2.56 m of paper per strip, and that extra 16 cm on every strip adds up to whole rolls.
Should I buy all the rolls at once?
Yes, and from the same batch. Wallpaper shade varies between print runs noticeably, and a roll from a different batch can be visibly different on the wall. The batch number is printed on the packaging and is worth checking on arrival.
What is a drop match?
A pattern staggered between adjacent strips rather than lining up at the same height. It wastes more paper than a straight match, because alternate strips start half a repeat apart. Allow extra beyond this calculation for an offset pattern.
How much extra should I allow?
Around 10% beyond the calculated rolls, which this reports as a separate figure. Wallpaper is unforgiving of mistakes, and a spare roll for a future repair is worth having given how hard batch matching becomes later.
For painting instead, see the paint calculator. For the board behind it, see the drywall calculator.