How to use
- Measure room length, width, and the wall height you intend to paper.
- Copy the roll width, usable roll length, and vertical repeat from the wrapper.
- Allow for trimming both ends of each strip, then calculate the number of whole rolls.
How the estimate is calculated
The perimeter is twice the sum of room length and width. Divide its width in inches by roll width and round up to obtain full-height strips. Add total trim to wall height; when there is a repeat, round this cut length up to a complete repeat. The roll length divided by cut length, rounded down, gives strips per roll. Finally divide required strips by strips per roll and round up.
Example: a 12 × 10 ft room with 8 ft walls has a 528 in perimeter. A 20.5 in wide, 33 ft long roll and 4 in total trim give 26 strips of 100 in. Each roll yields 3 strips, so the order is 9 rolls. Doors and windows remain included.
Read dimensions before roll names
| Input | Example figure | Basis |
|---|---|---|
| Roll width | 20.5 in | York double-roll listing reviewed only as a search summary |
| Roll length | 33 ft | Same commercial listing; check the actual wrapper |
| Gross area | 56.38 sq ft | 20.5 ÷ 12 × 33, before cuts |
| Total trim | 4 in | Changeable planning allowance |
A label may describe a single roll, a double roll, or a packaged set. Count the physical units that have the length entered here. Gross area is not usable wall coverage after cutting full strips.
Why repeats use more paper
In the example, a 21 in repeat raises each cut from 100 to 105 in. Three strips still fit a roll, so the order stays at nine; a longer cut can cross a yield boundary and require another roll. Straight match aligns neighboring motifs at the same height. Drop match offsets neighboring strips and may need a different cutting sequence or extra starting waste. This repeat rounding does not simulate that sequence.
Pooling the room perimeter also ignores individual corner seams. Lay out each wall when corners, feature walls, or drop matching make the strip positions important. Save useful offcuts for small patches, but do not assume an offcut will match above every opening.
Common mistakes
- Buying from advertised square feet alone while ignoring full-height strip yield.
- Subtracting every opening even though its surrounding strips still need to be cut.
- Entering trim for one end when the field asks for the combined top and bottom allowance.
- Mixing packaged roll length with a different roll-count convention.
Sources
Roll example: York double-roll listings, reviewed only as commercial search summaries. The listed dimensions are planning examples, not a universal York product specification. Repeat, match, and usable dimensions should be taken from your chosen wallpaper label. Unit conversion uses NIST's exact inch relationship.
Related calculators
- Paint Calculator — coverage for walls you choose to paint
- Square Footage Calculator — measure separate wall surfaces
Frequently asked questions
Are doors and windows removed?
They stay in this conservative perimeter estimate. Cut planning around openings determines whether any offcuts are reusable.
What repeat should I enter for plain wallpaper?
Use zero when the label says there is no pattern repeat. The cut length will then be wall height plus total trim.
Does the result handle drop match?
It rounds cuts to full repeats but does not sequence offset strips. Check the drop-match cutting instructions before using the order count.
Why can the calculator reject a short roll?
At least one full cut strip must fit in a roll. A roll shorter than the height plus trim cannot supply that strip.
Is the default roll size standard?
The default is a planning example from a York listing. Other wallpapers and packaging have different dimensions.