Case 1
- Wall area
- 30m²
- Roll length
- 10.05m
- Roll width
- 0.53m
- Waste allowance
- 15%
7rolls
Open with these valuesWallpaper Calculator
7rolls
Result: 7 rollsThe waste allowance is added to the wall area first, then the result is divided by what one roll covers and rounded up. A 30 m² wall at 15 % waste with 10.05 × 0.53 m rolls needs 7 rolls. The rounding comes last, because a part roll is still a whole purchase.
Worked examples
Case 2
- Wall area
- 40m²
- Roll length
- 10.05m
- Roll width
- 0.53m
- Waste allowance
- 10%
9rolls
Open with these valuesCase 3
- Wall area
- 20m²
- Roll length
- 5m
- Roll width
- 0.5m
- Waste allowance
- 0%
8rolls
Open with these valuesHow it's calculated
rolls = ⌈area × (1 + waste) ÷ (roll length × width)⌉
- StepAdd up the walls: width × height for each, in square metres.
- StepEnter the roll size; a Euro roll is 10.05 m long and 0.53 m wide.
- StepSet the waste allowance — 15 % for a pattern, about 10 % for plain.
- ResultThe count rounds up: an opened roll still has to be bought whole.
What this number means
A pattern repeat is paid for in length
The room is measured as an area, but paper hangs as drops, and a patterned drop can only start where its pattern meets the one beside it. That matching is what the allowance buys: 15 % for a pattern, about 10 % for plain paper with no repeat, 20 % or more for a large one.
One Euro roll covers 5.33 m²
10.05 m long by 0.53 m wide comes to 5.33 m² of paper before a single trim. A 30 m² wall at 15 % waste asks for 34.5 m², which is not quite seven roll-loads and therefore seven rolls.
The roll size is quoted, the 15 % is not
The source behind this calculator gives the Euro roll as 53 cm wide and 10.05 m long, and those are the defaults in the two roll fields. The 15 % allowance comes from decorating practice for patterned paper, not from that page.
Buy the whole job in one batch
Wallpaper is printed in runs and the colour shifts slightly between them. Buy every roll in one purchase under the same batch number, and set one roll from that batch aside for later repairs.
Commonly misread
My paper has no repeat, so I left the allowance at 15 %.
Plain paper with no repeat gets by on roughly 10 %, because no drop has to be matched to its neighbour. A large repeat runs the other way and wants 20 % or more.
I entered the roll width as 53, the number on the wrapper.
Both roll fields are metres, so a 53 cm roll is 0.53. Entered as 53 the roll appears to cover 533 m², and a single roll seems to paper the entire room.
I subtracted the door and the window from the wall area.
Openings interrupt the drops, and the strips left around them are often too short to use elsewhere. For most rooms it is safer to measure the wall as if it were solid and let the allowance absorb them.
Reference table
| Area, roll length, roll width, waste | Roll covers | Rolls |
|---|---|---|
| 20, 5, 0.5, 0 | 2.5 m² | 8 |
| 20, 10.05, 0.53, 15 | 5.33 m² | 5 |
| 30, 10.05, 0.53, 15 | 5.33 m² | 7 |
| 40, 10.05, 0.53, 10 | 5.33 m² | 9 |
| 50, 10.05, 0.53, 15 | 5.33 m² | 11 |
Questions
How many rolls of wallpaper do I need?
Multiply the wall area by the waste factor, divide by what one roll covers, then round up. A 30 m² wall with 10 × 0.53 m rolls at 15 % waste is 34.5 ÷ 5.3, which is 6.5 rolls and therefore 7.
How much waste should I add?
15 % is a sensible rule of thumb for a patterned paper, where each drop has to line up with the next. Plain paper with no repeat can drop to about 10 %, and a large repeat can need 20 % or more. Buying a little extra also leaves spares for later repairs.
Does the allowance apply before or after rounding?
Before. The allowance grows the area, the area is divided by the roll coverage, and only that final figure is rounded up to a whole roll. Rounding first and adding the allowance afterwards would over-order by a roll or two.
Does it matter which rolls I buy?
Yes. Wallpaper is printed in batches and colours vary slightly between runs. Buy all your rolls in one purchase with the same batch number, and keep a spare from that batch for repairs.
Should I subtract doors and windows?
For most rooms it is safer not to. Openings interrupt the drops, so the offcuts around them are often unusable and effectively become waste. Measuring the full wall and adding an allowance covers them without leaving you short.
Sources and last check
Information, not professional advice.