Ordering too little leaves a bare strip and a possible dye-lot mismatch. Ordering too much costs money. This guide shows a method you can run with a tape measure and a calculator.
What you need to know first
- Wall width and height in inches, measured at several points because walls are not always even.
- Panel width and panel length (or roll length) from the product page.
- Pattern repeat, if the pattern has one, which is how far you must go before the design starts again.
- Obstacles such as doors and windows. Measure them, but be careful about subtracting them.
The method
1. Work out how many strips you need across
Divide the wall width by the panel width, then round up.
strips = ceil(wall width ÷ panel width)
2. Work out the length of each strip
Add the wall height, a trim allowance and, if the pattern has a repeat, the repeat length. A trim allowance of a few inches top and bottom is common practice, but check your product’s guidance.
strip length = wall height + trim allowance + pattern repeat
3. Work out how many strips you get from a roll
Divide the roll length by the strip length and round down, since you cannot use a partial strip.
strips per roll = floor(roll length ÷ strip length)
4. Work out the number of rolls
rolls = ceil(strips ÷ strips per roll)
5. Add a safety margin
Add a little extra for mistakes, such as one more strip, or about 10 percent. A first project warrants more than a fifth.
Worked example (illustrative numbers)
Wall: 120 in wide, 96 in high. Suppose the product has a panel width of 20 in, roll length of 200 in and a pattern repeat of 12 in, and you allow 4 in of trim.
- Strips across: 120 ÷ 20 = 6
- Strip length: 96 + 4 + 12 = 112 in
- Strips per roll: 200 ÷ 112 = 1.79, rounded down to 1
- Rolls: 6 ÷ 1 = 6, plus a spare
Notice how the repeat changes things. With no repeat the strip is 100 in, a roll yields 2 strips, and you need 3 rolls. That is why a pattern with a large repeat can cost far more than its price per roll suggests.
Doors, windows and other cutouts
It is tempting to subtract their area, but wallpaper comes in strips, so you only save material if a whole strip can be avoided. Measure above and below openings and plan strips around them. When in doubt, do not subtract.
Accent walls and awkward walls
- Slopes and stair walls. Use the tallest point for strip length.
- Corners. Plan to cut the strip so a seam does not land exactly in the corner.
- Ceilings and bulkheads. Add extra, as cuts are harder and mistakes more likely.
Buy together
If your product has batches or dye lots, order everything at once and check that labels match. Keep any leftover for later repairs.
Checklist
- Measured the wall in at least two places
- Rounded strips up and strips per roll down
- Included trim and pattern repeat
- Added a safety margin
- Checked return terms before ordering
For choosing the product itself, see our buying checklist, and for protecting your wall see How to Choose Removable Wallpaper Without Damaging Your Walls.