Wallpaper Calculator
Work out how many rolls of wallpaper to buy. Enter your room dimensions and the roll specification — the calculator accounts for pattern-repeat waste, which is where most estimates go wrong.
Wallpaper Calculation Results
How the Wallpaper Calculator Works
Wallpaper is hung in vertical strips, so the calculation runs in strips, not square meters — and that's also where pattern repeat, the thing most estimates miss, enters the math.
Strips = perimeter ÷ roll width · Strip length = wall height rounded up to a full pattern repeat · Rolls = strips ÷ strips per roll
The room's perimeter divided by the roll width (standard: 53 cm) gives the number of strips. Each strip must be at least as long as your wall is high — but with a patterned paper, every strip must also start at the same point in the pattern to line up with its neighbor. That means each strip is cut to the wall height rounded up to a whole number of repeats. With a 2.5 m wall and a 32 cm repeat, every strip consumes 2.56 m of roll, and a standard 10.05 m roll suddenly yields 3 strips instead of 4. That single effect routinely adds two or more rolls to a room, which is why plain paper and large-repeat paper differ so much in cost.
How to Measure a Room for Wallpaper
Measure the wall height at the tallest point of the room — floors and ceilings drift, and a strip cut 2 cm short is scrap, while one cut 2 cm long just gets trimmed. Measure the full perimeter wall by wall, and resist the urge to subtract normal windows and doors: the offcuts around openings rarely align with the pattern elsewhere, so the "saved" paper mostly isn't usable. Only subtract genuinely large openings like patio doors or a wall of glass.
Find the pattern repeat printed on the roll label (drop patterns effectively double it — the label states the combined figure). Check batch numbers when the rolls arrive: like paint and flooring, wallpaper colors shift subtly between production runs, and two batches on one wall will show at certain angles forever.
Keep one uncut roll after the job for future repairs. If you're combining a papered feature wall with painted walls — the most common modern treatment — run the painted walls through our paint calculator and subtract the feature wall from that total. Tiled areas behind counters follow the same logic with the tile calculator.
Rolls Needed by Room Size (2.5 m walls, standard 53 cm × 10.05 m rolls)
| Room size | Plain paper | With 32 cm repeat | With 53 cm repeat |
|---|---|---|---|
| 3 × 3 m (12 m perimeter) | 6 rolls | 8 rolls | 8 rolls |
| 3 × 4 m (14 m perimeter) | 7 rolls | 9 rolls | 9 rolls |
| 4 × 5 m (18 m perimeter) | 9 rolls | 12 rolls | 12 rolls |
| 5 × 6 m (22 m perimeter) | 11 rolls | 14 rolls | 14 rolls |
Common Mistakes to Avoid
- Ignoring pattern repeat — the number one cause of running out one strip short.
- Subtracting every window and door; the offcuts rarely match the pattern where you need them.
- Mixing batch numbers on the same wall.
- Measuring wall height at one spot instead of the room's tallest point.
Frequently Asked Questions
How many rolls of wallpaper do I need for one wall?
Divide the wall's width by 0.53 m (standard roll width) and round up for the strip count, then divide the roll length by your strip length — wall height rounded up to a full pattern repeat — for strips per roll. A 4 m feature wall with 2.5 m ceilings needs 8 strips: 2 rolls of plain paper, 3 with a large repeat.
What does pattern repeat mean on wallpaper?
It's the vertical distance before the design repeats itself — printed on every roll label. Adjacent strips must align at the same point in the pattern, so each strip is cut to a whole number of repeats, wasting the remainder. Bigger repeat, more waste: a 64 cm repeat can add 20% to a room.
Should I subtract windows and doors when calculating wallpaper?
Usually no. The pieces you'd save around ordinary openings are offcuts that rarely match the pattern at the height you'd need them. Professional decorators calculate the full perimeter and treat the openings as margin. Only subtract very large glazed areas like patio doors or full-wall windows.
How much extra wallpaper should I buy?
The calculator's rounding already provides working margin, but add one extra roll — same batch number — as insurance and for future repairs. An uncut spare roll is cheap now and often unobtainable in a matching batch two years later. Check all batch numbers match at delivery.