Wallpaper calculator: rolls to buy from wall width and height, roll size, pattern repeat and trimming, counted as full-height drops per roll.
By AdminDrafted with AI writing toolsUpdated Checked examples: 3
Each strip is 2.65 m long, so one 10.05 m roll gives 3 strips. Covering 14 m of wall takes 27 strips, which means 9 rolls.
Wall height plus trimming, rounded up to whole pattern repeats so every strip starts at the same point in the pattern.
Rounded down: an offcut shorter than a drop can't be hung.
Rounded up; doors and windows are not subtracted because their offcuts rarely fit elsewhere.
Rounded up to whole rolls; 0 spare drops left over.
Wallpaper is bought by the roll but hung in drops, the full-height strips cut from it. Each drop is the wall height plus a trimming allowance, rounded up to whole pattern repeats so the design lines up. Drops across the walls are the total width divided by the roll width, rounded up; each roll gives its length divided by the drop length, rounded down; rolls to buy are drops divided by drops per roll, rounded up.
The default is 14 m of wall, 2.5 m high, papered with 53 cm × 10.05 m rolls and a 53 cm repeat. Each drop is 2.65 m, a roll yields 3, and 27 drops need 9 rolls.
Offcuts shorter than a drop are waste, which is why dividing wall area by roll area undercounts. The default 35 m² of wall divided by 5.33 m² per roll suggests 7 rolls; hanging it takes 9.
Divide the wall width by the roll width and round up to get drops, the full-height strips. Divide the roll length by the drop length and round down for drops per roll, then divide and round up. For 14 m of 2.5 m wall and 53 cm × 10.05 m rolls with a 53 cm repeat, buy 9 rolls.
A drop is the wall height plus a trimming allowance, rounded up to whole pattern repeats so the design lines up at each seam. The method fits paper hung in full-height strips; offset patterns are covered below.
Dividing area instead gives 35 m² ÷ 5.3265 m² per roll = 6.57, or 7 rolls. That is two rolls short, because each roll leaves a 2.10 m offcut too short to hang: 18.90 m across nine rolls.
On 14 m of 2.4 m high wall with 10 cm of trim, plain paper needs 2.50 m drops and a 10.05 m roll yields 4 of them. A 53 cm repeat stretches each drop to 2.65 m, a roll yields only 3, and the 27 drops take 9 rolls instead of 7.
The effect comes in steps. Because each drop rounds up to whole repeats, a few extra centimeters of height or trim can add a full repeat to every drop and cost one drop from every roll.
Graham & Brown's measuring guide separates free, straight and offset matches. The whole-repeat rule assumes a straight match, where every strip starts at the same point in the design.
Offset patterns and paired A/B rolls alternate their starting point. For those, follow the cutting sequence on the label before you order.
The default row is the worked example. Plain paper and patterned at same height use the same 14 m of wall at 2.4 m high, and exact ten widths is 5.3 m of plain paper at 2.4 m.
| Scenario | Drop length, m | Drops | Rolls |
|---|---|---|---|
| Default | 2.650000 | 27.000000 | 9.000000 |
| Plain paper | 2.500000 | 27.000000 | 7.000000 |
| Patterned at same height | 2.650000 | 27.000000 | 9.000000 |
| Exact ten widths | 2.500000 | 10.000000 | 3.000000 |
| US double rolls | 2.667000 | 24.000000 | 8.000000 |
The US row is 40 ft of 8 ft wall with 20.5 in × 33 ft double rolls, a 21 in repeat and 4 in of trim. Height plus trim is 100 in, or 4.76 repeats, so each drop is 105 in (2.667 m).
A 33 ft (396 in) roll gives 3 drops of 105 in, and 40 ft (480 in) of wall needs 24 drops, so 8 rolls.
The room area calculator gives a room's perimeter and gross wall area. For painted walls, use the paint calculator; if the walls need boarding first, the drywall calculator counts sheets.
Checked against: ⌈2.6/0.53⌉ × 0.53 = 2.65 m; ⌊10.05/2.65⌋ = 3; ⌈14/0.53⌉ = 27 drops; 27/3 = 9 rolls
Checked against: in inches: ⌈100/21⌉ × 21 = 105; ⌊396/105⌋ = 3; ⌈480/20.5⌉ = 24; 24/3 = 8
Checked against: Hand calculation: 5.3/0.53 = 10 drops exactly; 10.05/2.5 = 4 drops per roll; 10/4 = 2.5 → 3 rolls
Count drops, not square metres. Divide the total wall width by the roll width and round up for the drops; divide the roll length by the drop length and round down for drops per roll; then divide and round up. A 14 m perimeter with 2.5 m walls, 53 cm × 10.05 m rolls and a 53 cm repeat needs 27 drops at 3 per roll, so 9 rolls.
In the UK a standard roll is 10.05 m long and 0.53 m wide, about 5.3 m², according to TradeCalculator UK, which also lists 0.70 m wide rolls and other designer sizes. Because sizes vary by maker, enter the width and length printed on your roll's label.
Each drop is rounded up to a whole number of repeats so every strip starts at the same point in the pattern. On a 2.4 m wall with 10 cm for trimming, plain paper needs 2.5 m drops and a 10.05 m roll gives 4 of them. A 53 cm repeat makes each drop 2.65 m and a roll gives only 3, so 27 drops take 9 rolls instead of 7.
Usually not. Full-height drops are still hung beside a door and short pieces above and below a window, and those offcuts rarely fit elsewhere, so TradeCalculator UK papers the whole perimeter by default. Deduct only wide full-height openings such as patio doors: a 1.8 m opening is about 3 drops of 53 cm paper.
Colour can differ between production runs, so rolls from two batches may not match when hung side by side. Buy every roll you need with the same batch number at once, and add at least one spare roll for repairs and mistakes, as TradeCalculator UK recommends.
This calculator includes 3 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.