Wallpaper is sold by the roll and used by the drop, and the number of drops a roll gives depends on three things: the height of the wall, the length of the roll, and whether the pattern has to be matched. That last one is the one that costs money. With a plain paper, a ten-metre roll gives four drops on a 2.4 m ceiling. With a 32 cm pattern repeat it gives three, because each drop has to start at the same point in the pattern and the remainder is thrown away. That single difference is the difference between twelve rolls and sixteen on an average room.
Room, pattern and roll
A pattern repeat can cost you a third of a roll on every drop.
Round the room, including into the reveals if the paper goes there.
Standard European wallpaper is 53 cm; American is often 27 inches, about 69 cm.
On the label. Zero for a plain paper, 32 to 64 cm for a typical pattern.
50 mm top and bottom for trimming to the ceiling and the skirting.
Result
The pattern repeat is the whole game
A patterned paper has to line up. The motif has to be at the same height on every drop, which means each drop has to start at the same point in the pattern, which means you throw away whatever is left over between the last full repeat and the ceiling. On a 2.4 m ceiling with a 32 cm repeat, that is most of a repeat per drop, and across thirty-seven drops it adds up to around eleven metres of paper — more than a whole roll, thrown away.
This is why a patterned paper can need four rolls more than a plain one on the same room, and why the repeat figure on the label matters as much as the price. A 64 cm repeat on a 2.4 m ceiling wastes twice what a 32 cm one does, and a half-drop repeat — where the pattern matches on alternate drops rather than adjacent ones — wastes more again, because effectively every pair of drops needs matching rather than every drop.
Why the roll gives fewer drops than the arithmetic suggests
Divide ten metres by 2.82 and you get 3.55, which rounds down to three drops per roll. The remaining half-drop is unusable, because no drop in that room is 1.2 m long. So every roll contributes three drops and a piece of waste, and the waste is not a mistake — it is the geometry of a fixed roll length meeting a fixed drop length.
The practical consequence is that changing the roll length changes everything. European paper is typically 10.05 m; American double rolls are around 11 m; some suppliers sell by the metre from a larger roll. Going from 10.05 to 11 m on a 2.82 m drop still gives three drops — you need 11.28 for four — so nothing changes. It is worth checking before paying more for a longer roll that does not help.
Wallpaper is printed in batches and the colour varies between them. Buy everything for a room from one batch, in one order, including the spare.
Check the batch number on every roll before hanging. Two rolls that look identical under shop lighting can differ on the wall.
Measuring the room properly
Measure the perimeter at the height the paper will be hung, going into the reveals if the paper is going into them, and add a drop for each reveal. Subtract nothing for windows and doors at this stage: the drops either side of a doorway are full drops, and the piece over the door comes out of the offcuts rather than out of the count. That is the usual reason to add a roll.
A chimney breast adds two returns and usually two extra drops. A bay window adds several. A staircase wall is the awkward one: the drops are cut on a diagonal, and the length of the longest drop is what every drop has to be cut from, so a stair wall can use nearly twice what its area suggests.
| Paper | Width | Repeat | Waste | Note |
|---|---|---|---|---|
| Plain or textured | 53 cm | 0 | Lowest | Four drops a roll |
| Small motif | 53 cm | 16 cm | Low | Cheapest patterned option |
| Standard pattern | 53 cm | 32 cm | Moderate | The default case |
| Large motif | 53 cm | 64 cm | High | Consider a feature wall |
| Half-drop | 53 cm | 32 cm | Highest | Matches every other drop |
| Wide American | 69 cm | Varies | Lower | Fewer drops, so less waste |
A worked example
- DropsA 19.2 m perimeter at 53 cm is 37 drops.
- Drop length2.4 m of wall, 0.32 m of pattern match and 0.1 m of trim is 2.82 m per drop.
- Drops per rollA 10.05 m roll gives 3 drops, with 1.59 m left over.
- RollsThirty-seven drops at three a roll is 13 rolls, or $455 at $35.
- Against a plain paperWithout the repeat, each drop is 2.5 m and a roll gives four drops — 10 rolls. The pattern costs three rolls.
Three rolls, a hundred and five dollars, for a pattern. Sometimes that is exactly the right trade — and sometimes the answer is to paper one wall in the pattern and three in the plain version from the same range.
Hanging it
Start from a corner or from a door, and work away from the light. Measure and cut each drop with the pattern matched before it goes in the water or on the table, and number them on the back so they go up in order. Paste-the-wall papers are more forgiving than paste-the-paper, because there is no soaking time to get wrong.
Use a plumb line for the first drop only. Everything after it is aligned to the drop before, and if the first one is plumb and the walls are not, the pattern will drift — which is correct, because a drifting pattern is far less visible than a pattern that is square to a wall that is not.
The surface underneath matters more than the paper. Fill, sand and size the wall first, and the wall area figure gives the surface to prepare. If the walls are being boarded rather than skimmed, the drywall sheet figure sizes that, and the compound figure covers the jointing.
Do
- Read the pattern repeat off the label before ordering.
- Order everything in one batch, plus one roll spare.
- Add a drop for every reveal and every return.
- Hang from a plumbed first drop and align to the drop before.
- Prepare and size the wall before hanging.
Avoid
- Ordering by area and discovering the pattern needs four more rolls.
- Buying rolls from two batches and seeing the difference on the wall.
- Subtracting doors and windows from the perimeter.
- Forgetting a stair wall needs every drop cut to the longest one.
- Soaking paste-the-paper for the wrong time and stretching it.
Where the numbers stop being true
The calculation assumes every drop is the same length. On a stair wall, under a vaulted ceiling, or in a room with a dormer, the drops differ in length and each has to be cut from the longest. Where the variation is more than about a third of a metre, work out the longest drop and treat every drop as that long.
Nothing here accounts for a half-drop pattern, which matches on alternate drops and effectively doubles the matching waste. If the label says half-drop, add around twenty percent to the roll count rather than working it out precisely.
And there is no allowance for the piece over a door or above a fitted wardrobe, which has to match the drops either side of it and frequently cannot come from the offcuts. On a room with two doors, allow an extra roll.
How the figures are produced
Drops are the perimeter divided by the roll width, rounded up. Each drop is the ceiling height plus the pattern repeat plus the trim allowance. Drops per roll is the roll length divided by the drop length, rounded down, because a partial drop is unusable. Rolls are drops divided by drops per roll, rounded up. The plain-paper comparison repeats the calculation with a repeat of zero, which is what the pattern is costing you.
Questions people ask
Why do I need so many more rolls than the area suggests?
The pattern repeat. Each drop has to start at the same point in the pattern, so part of every drop is cut off and thrown away.
How much should I add for a half-drop pattern?
About twenty percent. A half-drop matches on alternate drops, which roughly doubles the matching waste.
Do I subtract doors and windows?
No. The drops either side are full drops, and the piece over the opening comes from the offcuts or from an extra roll.
How many drops does a roll give?
Three on a 2.4 m ceiling with a 32 cm repeat; four if the paper is plain. Check the repeat on the label.
Should I buy an extra roll?
Yes, one. From the same batch, for repairs and for the piece over the door.
Can I mix two batches?
Not on the same wall. The colour difference is invisible in the shop and obvious in daylight.