Enter measured room length, width and wall height, excluded opening area, the supplier’s usable coverage for the actual purchased roll unit and a separately chosen allowance. The 56 ft² coverage and 15% allowance are example inputs, not standard usable yields. Distinguish single-roll pricing from double-roll packaging and account for strip length and pattern repeat.
This area model does not lay out full-height strips or pattern matching. If usable coverage already includes cutting loss, adding the same loss again overstates the allowance. Roll dimensions, pattern repeat, drop match and ordering units affect wallpaper purchases.
Wallpaper: worked example
| Room length (ft) | 14 |
|---|---|
| Room width (ft) | 12 |
| Wall height (ft) | 8 |
| Doors and windows area (sq ft) | 65 |
| Usable coverage per roll (sq ft) | 56 |
| Waste allowance | 15.0% |
| Rolls needed | 8 |
| Paper area to cover (sq ft) | 351 |
Common error: Buying the rolls in two trips. Print runs vary, and a second batch can show a slight shade difference on the wall.
Wallpaper: formula
NIST Handbook 44: Units and Systems of Measurement · Rectangle: Wolfram MathWorld
Wallpaper: changing Room length (ft)
| Room length (ft) | Rolls needed | Paper area to cover (sq ft) |
|---|---|---|
| 11 | 7 | 303 |
| 13 | 7 | 335 |
| 14 (example) | 8 | 351 |
| 15 | 8 | 367 |
| 17 | 9 | 399 |
Wallpaper: compare input ranges
| Input | Tested from | To | Rolls needed: low input | Rolls needed: high input | Swing |
|---|---|---|---|---|---|
| Wall height (ft) | 7 | 9 | 7 | 9 | 2 (25%) |
| Usable coverage per roll (sq ft) | 50 | 62 | 9 | 7 | 2 (25%) |
| Room length (ft) | 13 | 15 | 7 | 8 | 1 (13%) |
| Room width (ft) | 11 | 13 | 7 | 8 | 1 (13%) |
| Doors and windows area (sq ft) | 59 | 72 | 8 | 8 | 0 |
| Waste allowance | 13.0% | 17.0% | 8 | 8 | 0 |
Wallpaper: individual input comparisons
| Input | Value | Rolls needed | Paper area to cover (sq ft) |
|---|---|---|---|
| Room length (ft) | 11 | 7 | 303 |
| 13 | 7 | 335 | |
| 14 | 8 | 351 | |
| 15 | 8 | 367 | |
| 17 | 9 | 399 | |
| Room width (ft) | 10 | 7 | 319 |
| 11 | 7 | 335 | |
| 12 | 8 | 351 | |
| 13 | 8 | 367 | |
| 14 | 8 | 383 | |
| Wall height (ft) | 6 | 6 | 247 |
| 7 | 7 | 299 | |
| 8 | 8 | 351 | |
| 9 | 9 | 403 | |
| 10 | 10 | 455 | |
| Doors and windows area (sq ft) | 52 | 8 | 364 |
| 59 | 8 | 357 | |
| 65 | 8 | 351 | |
| 72 | 8 | 344 | |
| 78 | 7 | 338 | |
| Usable coverage per roll (sq ft) | 45 | 9 | 351 |
| 50 | 9 | 351 | |
| 56 | 8 | 351 | |
| 62 | 7 | 351 | |
| 67 | 7 | 351 | |
| Waste allowance | 11.0% | 7 | 351 |
| 13.0% | 8 | 351 | |
| 15.0% | 8 | 351 | |
| 17.0% | 8 | 351 | |
| 19.0% | 8 | 351 |
Wallpaper: combined input changes
| Room length (ft) / Room width (ft) | 10 | 12 | 14 |
|---|---|---|---|
| 11 | 6 | 7 | 7 |
| 13 | 7 | 7 | 8 |
| 14 | 7 | 8 | 8 |
| 15 | 7 | 8 | 9 |
| 17 | 8 | 9 | 9 |
Wallpaper: which assumptions move the result?
Wallpaper: values and definitions
| Quantity and definition | Value used |
|---|---|
| Room length (ft) | 14 |
| Room width (ft) | 12 |
| Wall height (ft) | 8 |
| Doors and windows area (sq ft) — Add up the area of each door and window you will not paper. | 65 |
| Usable coverage per roll (sq ft) — Printed on the roll. Use the supplier’s measured roll dimensions and distinguish single-roll pricing from double-roll packaging. | 56 |
| Waste allowance — Pattern matching wastes more than a plain paper. | 15.0% |
| Rolls needed | 8 |
| Paper area to cover (sq ft) | 351 |
Wallpaper: half and double Wall height (ft)
| Wall height (ft) | Rolls needed |
|---|---|
| 4 | 3 |
| 8 | 8 |
| 16 | 16 |
Home & Construction calculators: Carpet Calculator, Rainwater Harvesting Calculator, Cubic Feet, Yards and Meters Calculator, Flooring Calculator, Material Volume and Bag Calculator, Tile Flooring Calculator.
Wallpaper is sold in rolls, not by area, and each roll covers less than its label suggests once the pattern is matched. A 14 by 12 foot room with 8 foot walls has 416 square feet of wall, less 65 for a door and windows. With 15 percent waste over 56 square feet a roll, that comes to eight rolls, even though the raw area suggests closer to six.
Look at the pattern repeat on the label. A large repeat wastes more paper at every seam, so raise the waste allowance to match.
Compare with painting on the paint calculator, estimate the wall area on the square footage page, and see the drywall calculator for the wall surface. The tile and flooring pages cover other finishes, and the unit price comparison calculator helps compare paper prices.
How many rolls of wallpaper do I need?
Divide the wall area to be covered, with waste, by the usable coverage per roll, then round up.
What is a pattern repeat?
The vertical distance before the pattern repeats. Larger repeats need more paper so that patterns line up between strips.
Why buy all the rolls at once?
Different print runs can vary in color, so rolls from a single batch match better and hide the seams between strips.