Wall & Ceiling
Wallpaper Roll Calculator
Estimates rolls with straight match and half-drop pattern repeat
Updated 13 May 2026 · Live
What this tool does
Estimates rolls with straight match and half-drop pattern repeat.
Formula Used
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How the wallpaper calculator works
This calculator estimates how many rolls of wallpaper a room needs. It takes the wall area to cover, adds a wastage allowance for pattern matching and trimming, divides by the coverage of one roll, and rounds up to whole rolls. It also shows an indicative cost from the price per roll you enter. A standard UK roll is about 10 m long and 0.52 m wide, giving roughly 5 m² of coverage before matching.
Wallpaper wastage and pattern repeat
The default wastage allowance is 15%, higher than for paint because each drop is cut to the wall height and, on patterned papers, aligned to the next. A straight match lines the pattern up at the same height across the wall; a half-drop match offsets alternate drops, so the offcut from one drop rarely fits the next. Larger pattern repeats waste more, and plain or random-match papers waste less, so the allowance can be adjusted to the paper.
What this tool does not do
It does not subtract specific door and window openings, calculate drops per roll for an exact pattern repeat, or confirm the paste type for your paper. It does not replace a professional quote or factor regional pricing. The roll length, width and repeat printed on the product label give the figures for a precise drop-by-drop take-off.
Working from wall area
The wall area is the height multiplied by the perimeter of the papered walls. Openings such as doors and large windows can be deducted, though many decorators paper past small openings and trim, keeping a margin for matching. A feature wall is simply the area of the single wall being papered.
On-site considerations
Rolls from different batches can vary slightly in shade, so a single batch covering the whole room gives the most even finish. Coverage on the label is a nominal figure before pattern matching and trimming at skirting and coving, which the wastage allowance is there to absorb.
Adjusting the defaults
Every input here is editable. Enter your own wall area, roll coverage, wastage allowance and price per roll, and the count and cost recalculate instantly. If a default does not match your paper or room, your own numbers always take precedence.
Using this wallpaper calculator alongside other BuildMetricLab tools
This calculator works best as part of a wider plan. Pair the roll count with our project contingency and labour-cost calculators to build a complete estimate before contacting a supplier. All BuildMetricLab tools run entirely in your browser — no sign-up, no data sent anywhere, and every formula is shown on-page so you can audit the maths.
Sources & methodology
Estimates rolls with straight match and half-drop pattern repeat. Every result is calculated from the values you enter, and all inputs are editable.
Frequently asked questions
Are wallpaper roll calculator results accurate enough to order materials?
Use them as a starting estimate only. Verifying the final quantity with your supplier or contractor before ordering is good practice — site conditions, wastage and cut-offs all affect the true figure.
What wastage percentage should I use?
The default is 15%, higher than for paint because each drop is cut to the wall height and aligned to the pattern. Straight-match and plain papers waste less; large half-drop repeats waste more. A figure below 15% risks running short once pattern matching and trimming are counted.
Does this replace professional advice?
No. This tool is a planning estimator. For works that affect structure, Building Regulations, Party Wall, gas, electrics, drainage to a sewer, or similar, consult a suitably qualified professional.
Can I change the unit prices?
Yes — every price field is editable. Plug in your supplier's quote to get a total that matches your project.
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