Wallpaper calculator
Estimate wallpaper rolls from perimeter, height, roll width and length, pattern repeat, trimming allowance and budget.
This choice applies to every calculator; amounts are not converted.
Wallpaper calculation
Calculate drops and rolls while accounting for wall height, roll format and pattern repeat.
Waste per roll
Budget
Calculation details
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How does this tool work?
Wallpaper is not counted in m² but in vertical drops cut from rolls of fixed length, and the pattern repeat can waste a whole drop per roll. This calculator takes the room dimensions or the combined length of the walls to paper, the ceiling height, the roll size, the pattern repeat and the trim allowance, then returns the actual drop length, the number of drops, how many fit in one roll, the rolls to buy, the offcut per roll and, if you enter a price, the budget.
In room mode, wall length is the perimeter 2 × (length + width); in wall mode, you enter the combined length of the walls to paper directly. That length divided by the roll width, increased by the allowance and rounded up, gives the number of drops.
Drop length is height + trim. With a pattern, it is rounded up to the next multiple of the repeat so every drop starts at the same point of the design: 2.80 m with a 68 cm repeat becomes 3.40 m.
Drops per roll is the whole number part of roll length ÷ drop length. Rolls to buy equal drops ÷ drops per roll, rounded up, and the offcut per roll is the unusable remainder.
Limits: doors and windows are not deducted, as offcuts are often used above and below openings. The calculation assumes a straight match; a half-drop or offset match may need slightly more paper according to the label. Ceilings, sloping walls and papers hung horizontally are not covered. Substrate preparation and hanging rules (manufacturer instructions, or NF DTU 59.4 in France) remain the reference.
Wallpaper yield depends on how many full drops can be cut from a roll, not only on the roll’s total area. A large pattern repeat may require each drop to be shifted and can materially reduce the number of usable drops per roll.
How to use this tool
Choose the measuring mode
Whole room to enter length and width, or wall length for a few walls only, then the ceiling height.
Enter the roll
Take the width in centimetres and the length in metres from the label, for example 53 cm × 10.05 m.
Add repeat and trim
Enter the repeat shown on the label, 0 for a plain or free match, and about 10 cm of trim.
Read rolls and offcut
Check the drop length and drops per roll, then note the rolls to buy and the estimated price.
Drops and rolls
Wallpaper is counted in drops, not square metres.
Drops needed
D = ⌈P ÷ w × (1 + allowance)⌉
P wall length, w roll width.
Drop length
Ld = ⌈(H + trim) ÷ repeat⌉ × repeat
Without repeat, Ld = H + trim.
Rolls
Rolls = ⌈D ÷ ⌊roll length ÷ Ld⌋⌉
Only whole drops are usable in a roll.
Openings are not deducted: a window rarely removes a full drop. Check the batch number so every roll matches in shade.
Use cases
Fully papered bedroom
Enter length, width and height of a 10 to 15 m² room and get the rolls for all four walls.
Feature wall behind a bed or sofa
Switch to wall mode, enter 3 to 4 m and order only the rolls for the decorated wall.
Choosing between plain and patterned
Compare a paper with no repeat and a large-repeat design to see the difference in rolls and budget before choosing.
Examples
4 × 3 m bedroom, no pattern match
14 ÷ 0.53 = 26.4 drops, 27.7 with the allowance, rounded to 28. Three 2.60 m drops fit in 10.05 m: 28 ÷ 3 = 9.3, so 10 rolls.
Input
Room 4 × 3 m, height 2.50 m, roll 0.53 × 10.05 m, repeat 0, trim 10 cm, 5% allowanceResult
14 m of wall, 28 drops of 2.60 m, 3 drops per roll, 10 rolls, 2.25 m offcut per roll14 m of wall, 2.70 m high, 68 cm pattern repeat
2.80 m rounded up to the repeat gives 5 × 0.68 = 3.40 m per drop: a third drop no longer fits in the roll, taking the count from 10 to 14 rolls.
Input
Wall length 14 m, height 2.70 m, roll 0.53 × 10.05 m, repeat 68 cm, trim 10 cm, 5% allowanceResult
28 drops of 3.40 m, 2 drops per roll, 14 rolls, 3.25 m offcut per rollTips and best practices
- Check the batch number on every roll: two batches can show a slight colour difference once hung side by side.
- If the offcut per roll is close to one drop length, a slightly shorter trim or an exact height can gain one drop per roll.
- Wide rolls of 70 cm or 1.06 m reduce the number of drops and seams to match: enter their actual width to compare.
- Keep one full roll aside for repairs, especially with a pattern that may be discontinued.
Sources and references
Frequently asked questions
Should doors and windows be deducted?
Not necessarily when counting rolls: an opening does not always remove a full drop. A conservative estimate keeps a useful reserve.
What is the pattern repeat?
It is the distance after which the pattern repeats. The length of each drop may need to be rounded up to the next multiple.
Why does a pattern repeat increase the number of rolls?
Because each drop has to start at the right point of the pattern, which creates more offcuts.
How many rolls for a 12 m² bedroom?
Floor area is not enough: you need the perimeter and the height. A 4 × 3 m room with 2.50 m walls takes 10 standard 0.53 × 10.05 m rolls with no pattern match, more with a repeat.
What should I enter as trim?
The length added to each drop for trimming at top and bottom, often 5 cm at each end, so 10 cm in total. An uneven ceiling or floor justifies more.
Can I use it for a ceiling?
No, it counts vertical drops on walls. For a ceiling, count strips across the shorter room dimension and keep a spare roll, as hanging is trickier.
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