Wallpaper Calculator
Calculate how many rolls of wallpaper a room needs from its perimeter and height, the roll dimensions, and the pattern repeat that adds waste to every strip.
كيفية استخدام هذه الحاسبة
- 1Measure and add up the length of all walls to get the perimeter.
- 2Enter the wall height and the roll's length and width.
- 3Enter the pattern repeat (0 for plain paper) and subtract strips for big openings.
- 4Read the number of rolls, and buy one extra from the same batch.
طريقة الحساب
Wallpaper rolls
drop length = height + trim, rounded up to a whole pattern repeat strips per roll = ⌊roll length ÷ drop length⌋ strips needed = ⌈perimeter ÷ roll width⌉ rolls = ⌈strips needed ÷ strips per roll⌉
Wallpaper is hung in vertical strips, called drops, so the honest way to estimate it is to count strips rather than divide by area. First work out how long each drop must be: the wall height plus a small trimming allowance, and — crucially — rounded up to a whole number of pattern repeats so the design lines up across every seam. Divide the roll length by that drop length and round down to see how many usable strips one roll yields, since a leftover shorter than a full drop is wasted. Then divide the room's perimeter by the width of the paper and round up to find how many strips are needed to wrap the walls. Dividing strips needed by strips per roll, rounded up, gives the number of rolls. This strip-counting approach captures the real waste that an area calculation hides, especially the material lost to pattern matching.
مثال محلول
A room with a 16 m perimeter and 2.4 m walls, using 10 m × 0.53 m rolls of plain paper, needs drops of about 2.5 m (height plus trim). Each roll yields ⌊10 ÷ 2.5⌋ = 4 strips, and the walls need ⌈16 ÷ 0.53⌉ = 31 strips — so ⌈31 ÷ 4⌉ = 8 rolls. A large pattern repeat would lengthen each drop and could push it to 9 or 10.
Wallpaper Calculator: الدليل الكامل
Why wallpaper is counted in strips, not area
It is tempting to estimate wallpaper the way you would paint — total the wall area and divide by the coverage of a roll. This under-orders almost every time, because wallpaper is applied in full-height vertical strips and the leftover at the bottom of a roll usually cannot be used. If a 10-metre roll yields four full 2.4-metre drops, the remaining 0.4 metres is scrap; the area calculation would count it as usable and leave you short. Counting whole strips per roll, and rounding down, reflects how the material is actually cut and hung.
This is why professional estimates always work in drops. The number of strips a room needs is set by its perimeter divided by the paper's width, and the number a roll provides is set by its length divided by the drop height. Keeping these two counts separate — strips needed versus strips per roll — is the key to an accurate order. It also makes the effect of wall height obvious: taller walls yield fewer drops per roll, so a high-ceilinged room needs disproportionately more rolls than its floor area suggests.
The hidden cost of the pattern repeat
The single biggest source of wallpaper waste is the pattern repeat — the vertical distance over which the design repeats itself. For the pattern to line up across the seams between strips, each new drop must start at the same point in the pattern as its neighbour, which means cutting each drop to a whole number of repeats rather than just the wall height. A paper with a 60-centimetre repeat and a 2.4-metre wall forces drops of a full three metres (five repeats), wasting more than half a metre at the top of every single strip.
This is why two papers with identical roll sizes can require very different numbers of rolls: the one with the larger repeat wastes more per drop and yields fewer usable strips per roll. Patterns also come as 'straight match', where adjacent strips align at the same height, or 'drop match', where alternate strips are offset, which wastes still more. Plain papers and small repeats are the most economical; a bold, large-repeat design is beautiful but material-hungry. The calculator's repeat field is what turns a rough guess into a realistic order.
Batches, spares, and ordering wisely
Wallpaper is printed in production runs called batches or dye lots, and colour can vary subtly between them. Two rolls of the same design from different batches may show a faint but visible difference in shade where they meet on a wall — an effect that is maddening once noticed and impossible to fix without re-papering. The rule is to buy all the rolls for a room in one order from a single batch, and to check the batch numbers on the labels match before starting.
For the same reason, it is wise to order at least one roll more than the calculation demands. It covers mistakes, awkward cuts around obstacles, and future repairs if a strip is damaged, all from matching stock. Trying to top up later risks a batch mismatch or, with discontinued designs, no match at all. The cost of a spare roll is trivial next to redoing a wall, so treat the calculator's figure as the minimum and round up when the paper is expensive, the pattern is complex, or the room is one you cannot easily re-do.
الأسئلة الشائعة
How many rolls of wallpaper do I need?
Count strips, not area. Divide the roll length by the drop height (wall height plus trim, rounded to a whole pattern repeat) for strips per roll, and divide the room perimeter by the paper width for strips needed. Divide one by the other and round up. Then add a spare roll.
Why does the pattern repeat matter?
Because each drop must be cut to a whole number of repeats so the pattern lines up across seams, wasting material at the top of every strip. A large repeat can waste half a metre per drop, meaning fewer usable strips per roll and more rolls needed than a plain paper.
Should I calculate wallpaper by area?
No — area under-orders, because the leftover at the bottom of each roll usually can't be reused once the pattern must align. Counting whole full-height strips per roll, and rounding down, reflects how paper is actually cut and gives an accurate roll count.
Why buy wallpaper from the same batch?
Wallpaper is printed in batches (dye lots) that can differ subtly in colour. Rolls from different batches may show a visible shade difference where they meet. Buy all your rolls in one order, check the batch numbers match, and order a spare for repairs from the same batch.