Dividing wall area by roll area underestimates wallpaper. Paper goes on in vertical strips, called drops, and every strip has to be cut a little long for trimming and to line up the pattern with the strip beside it. The offcuts from the end of each roll are usually too short to use. The reliable way to estimate is the strip method: work out how many strips cover the wall width, how many full-length strips you can cut from one roll, and divide. This wallpaper calculator does exactly that. It supports European rolls (0.53 × 10.05 m), US double rolls and custom sizes, includes pattern repeat and trim allowance, and adds a spare roll.
Papering one wall and painting the rest? Size the paint with the paint calculator. Rolls vary a lot by brand, so always check the label for width, length and repeat.
How to use the wallpaper calculator
- Measure the width of each wall you will paper and add them together, or measure the room perimeter.
- Measure the wall height from the baseboard to the ceiling.
- Enter the width of anything full-height you will skip, such as doors or built-ins. Leave windows in: strips above and below them still use most of a strip.
- Find the pattern repeat on the label or sample. Enter 0 for random-match papers.
- Choose the roll size or enter the label dimensions, and keep one spare roll. Rolls from a different batch can differ slightly in color.
Formula
Rounding the strip up to a whole number of repeats keeps the pattern aligned from strip to strip for a straight match. Half-drop patterns can be cut a little more efficiently by alternating strips from two rolls, but the same estimate is a safe ceiling.
Worked example
A 12 ft accent wall, 8 ft high, with a 21-inch repeat on US 20.5 in × 33 ft double rolls, 4 in trim, and one spare.
- Strip: 96 + 4 = 100 in, rounded up to a whole repeat: 5 × 21 = 105 in (8.75 ft).
- Strips per roll: 33 ÷ 8.75 = 3.77, so 3.
- Strips needed: 144 ÷ 20.5 = 7.02, so 8.
- Rolls: 8 ÷ 3 = 2.67, so 3, plus 1 spare = 4 rolls.
A plain random-match paper on the same wall needs 100-inch strips: still 3 per roll, so the same 3 rolls plus a spare. Large repeats cost paper quickly. Farrow & Ball estimates two drops per roll for large repeats in a standard 2.4 m room, three for small repeats and four for stripes.
Common roll sizes
| Roll | Width × length | Area |
|---|---|---|
| European (standard) | 0.53 × 10.05 m (20.9 in × 33 ft) | 5.33 m² (57.3 ft²) |
| Farrow & Ball | 0.53 × 10 m | 5.3 m² (57.0 ft²) |
| US double roll | 20.5 in × 33 ft | 56.4 ft² |
| US double roll (wide) | 27 in × 27 ft | 60.8 ft² |
US wallpaper is often priced by the single roll but sold in double rolls. Check whether a price is per single or per double roll before comparing. Peel-and-stick and designer papers come in many other sizes, so use the custom option.
Avoiding shortfalls
Order everything at once and check that every roll has the same batch or run number. Farrow & Ball advises adding one more roll than you estimate, to allow for trimming or mistakes, because colour can differ slightly between batches. York's installation guide suggests about 4 inches of extra length per strip, roughly 2 inches at the ceiling and 2 inches at the baseboard, and reminds installers to account for the pattern repeat and match. Walls that are out of plumb, sloped ceilings and stairwells add waste. For a stairwell, measure the tallest strip and use that height. Prime the wall first as the product instructions direct. The baseboard & trim calculator helps if you're replacing trim at the same time.
Caveats and assumptions
- Strip counts assume every strip is cut full-height from one roll; offcuts may fit above doors and windows, which can save a little.
- Half-drop and large-scale murals follow the manufacturer’s own layout; check their estimate.
- Rolls vary by brand; always use the label’s width, length and repeat.
- Keep the spare roll for future repairs from the same batch.
Frequently asked questions
How many rolls of wallpaper do I need for an accent wall?
For a 12 × 8 ft wall with a 21-inch repeat on 20.5 in × 33 ft rolls, 8 strips at 3 per roll, so 3 rolls plus a spare.
How many strips do you get from a roll of wallpaper?
Divide the roll length by the strip length (wall height plus trim, rounded up to the repeat) and round down. A 33 ft roll gives 3 strips of 8¾ ft.
How do I account for pattern repeat?
Round each strip length up to a whole number of repeats so the pattern lines up. Larger repeats waste more paper per strip.
How big is a standard roll of wallpaper?
European rolls are commonly 0.53 × 10.05 m (about 57 ft²). US double rolls are often 20.5 in × 33 ft or 27 in × 27 ft. Check the label.
Should I subtract windows and doors?
Subtract full-height doors and built-ins, but not windows. The pieces above and below a window still use most of a strip.
Sources
- York Wallcoverings — Wallpaper Installation Guide — about 4 in trim allowance; pattern repeat and match
- Farrow & Ball — Calculating Wallpaper Quantities — 10 m × 53 cm rolls, drops per roll, add one more roll
- NIST SP 811, Appendix B — conversion factors — metric to US units
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.