How to measure a room for wallpaper
Measure the length and width of the room in feet and the wall height from the top of the baseboard to the ceiling (or to the crown molding). The calculator finds the perimeter, multiplies by height, and subtracts a typical 20 sq ft per door and 15 sq ft per window. If you are papering only one accent wall, it is simplest to multiply that wall's width by its height and divide by your roll coverage yourself, or enter the wall width as the length and 0 as the width, then halve the result.
Finding the roll coverage
Wallpaper roll sizes vary a lot. In the US, many papers are sold in double rolls priced as two single rolls, and European rolls are a different size again. The label or product page lists the usable coverage in square feet, and that is what goes in the "Coverage per roll" box. Our default of 28 sq ft is only a placeholder; always use your label's number. Note whether the price and coverage are per single roll or double roll.
The formula
Net wall area = perimeter × height − (doors × 20) − (windows × 15). Rolls = net area × (1 + waste %) ÷ coverage per roll, rounded up.
Worked example
A 12 ft × 10 ft room with 8 ft walls, one door and two windows, using a patterned paper with 28 sq ft per roll and 15% waste:
- Perimeter: 2 × (12 + 10) = 44 ft
- Wall area: 44 × 8 = 352 sq ft, minus 20 and 30 = 302 sq ft
- Add 15%: 347 sq ft
- 347 ÷ 28 = 12.4, so 13 rolls
Waste and pattern repeat
Every strip must be cut so the pattern lines up with the strip next to it, and the leftover between repeats is waste. The larger the pattern repeat, the more you lose:
- Plain, textured or "random match" papers: about 10%
- Small repeats: about 10–15%
- Large repeats (roughly 18 in or more) or drop matches: about 15–20% or more
The repeat length and match type are printed on the label. When in doubt, ask the retailer to check your measurements.
Common mistakes
- Using the wrong roll size. Mixing up single and double rolls doubles or halves your order.
- Buying from different batches. Wallpaper is printed in batches (also called runs or lots), and colors can shift slightly between them. Buy all rolls with the same batch number, plus a spare.
- Skipping wall prep. Walls should be clean, smooth and primed with a primer suited to wallpaper, which also makes future removal easier.
- Starting in a corner. Corners are rarely plumb. Most installers snap a plumb line for the first strip.
Buying tips
- Check whether the paper is pre-pasted, paste-the-wall or paste-the-paper. Each needs different tools and adhesive.
- Peel-and-stick wallpaper is popular for renters and accent walls. It is often sold in narrower rolls with different coverage, so enter the specific number.
- Order one extra roll from the same batch. It is cheaper than trying to match a discontinued pattern later.
- Basic tools: smoothing brush or plastic smoother, sharp snap-off knife with spare blades, seam roller, level and sponge.
Smoother, knife and seam roller