How to use the wallpaper calculator
Wallpaper is hung in vertical strips called drops, and the pattern has to line up from one drop to the next. That is why dividing wall area by roll area nearly always underestimates the order. This calculator follows the method decorators use: it works out how long each drop really is once the pattern repeat and trimming are allowed for, how many whole drops you get from a roll, and how many drops each wall needs.
- Choose metric or US units. Walls and roll length are in metres or feet; roll width, repeat and trim are in centimetres or inches.
- List the wall widths separated by commas, for example 4.2, 3.6, 4.2, 3.6 for a whole room or a single number for a feature wall.
- Enter the wall height from floor or skirting to ceiling, and the total width of any wide openings you won't paper.
- Pick a roll size or enter your own, then enter the pattern repeat and match type from the label.
- Read the drop length, drops per roll and rolls to buy, and order the figure with a spare roll from a single batch.
Wallpaper formulas
Drop length = ⌈(height + trim) ÷ repeat⌉ × repeat (+ ½ repeat for half-drop)
Drops per roll = ⌊roll length ÷ drop length⌋
Drops needed = Σ ⌈wall width ÷ roll width⌉ − ⌊openings ÷ roll width⌋
Rolls = ⌈drops needed ÷ drops per roll⌉
Rounding per wall matters: a 3.6 m wall with 0.53 m paper needs 6.8 drops, which means 7, and you can't use the leftover strip on the next wall without breaking the pattern at the corner. The area method is shown alongside for comparison, so you can see how much the pattern and the offcuts add.
| Roll | Width | Length | Area |
|---|---|---|---|
| European standard | 0.53 m | 10.05 m | 5.33 m² |
| European wide | 0.70 m | 10.05 m | 7.04 m² |
| Extra wide (vinyl, mural) | 1.06 m | 10.05 m | 10.65 m² |
| US double roll | 20.5 in | 33 ft | 56.4 ft² |
| US double roll, wide | 27 in | 27 ft | 60.8 ft² |
These are common sizes rather than a standard every maker follows, so always check the roll label.
Worked examples
A bedroom in standard European rolls
Walls of 4.2, 3.6, 4.2 and 3.6 m, 2.5 m high, with 0.53 × 10.05 m paper and a 53 cm straight-match repeat. Height plus 10 cm trim is 2.6 m, which rounds up to five repeats, so each drop is 2.65 m and a roll gives three drops. The 4.2 m walls need 8 drops each and the 3.6 m walls 7 each, so 30 drops, or 10 rolls. Buy 11 with a spare. The area method would have said 39 m² ÷ 5.33 = 8 rolls, two short.
A feature wall with a large half-drop pattern
One 3.8 m wall, 2.7 m high, with 0.53 m paper and a 64 cm half-drop repeat. Height plus trim is 2.8 m, which rounds up to 3.2 m, plus 0.32 m for the half-drop, so each drop is 3.52 m and a roll yields only two. The wall needs 8 drops, so 4 rolls, or 5 with a spare.
A US dining room
Walls of 12, 14, 12 and 14 ft, 8 ft high, with 20.5 in × 33 ft double rolls and a 21 in repeat. Height plus a 4 in trim is 100 in, which rounds up to 105 in, so each roll gives three 8.75 ft drops. The walls need 8 + 9 + 8 + 9 = 34 drops, so 12 double rolls before the spare. Skipping a 6 ft wide opening saves 3 drops and one roll.
Who this calculator helps
- Interior designers and architects specifying wallcoverings and checking quantities on a finishes schedule.
- Decorators and painters quoting a job and ordering stock from one batch.
- Retailers and showrooms giving customers an accurate roll count at the counter.
- Homeowners pricing a feature wall or a whole room before ordering samples.
- Hospitality and workplace fit-out teams costing large runs of commercial wallcovering.
Practical tips
- Check every roll has the same batch number before you start, and keep the labels for reordering.
- Start hanging from the least visible corner, because the last drop rarely matches the first.
- For walls you plan to paint instead, use the paint calculator, and plan the scheme with the room colour palette generator.
- Pair wallcovering choices with the floor and joinery finishes in the material palette builder.
- Lining paper under a heavy wallpaper uses the same drop method without a repeat, so run the calculator again with free match.
Want to see a pattern or colour on the actual walls before ordering? Try it on a photo of the room with Wall Paint, or restyle the whole space with Room Redesign.
