Wallpaper Calculator
Rolls of wallpaper for a room from wall size, roll width and length and the pattern repeat — the repeat is what really drives waste, and this shows how much.
Wallpaper Calculator: with the default inputs, rolls to buy is 10.
Use total wall length for one feature wall, a hallway or a room with jogs.
Floor to ceiling, or to the picture rail if you stop there.
American rolls are 20.5 in (52 cm); European rolls 53 cm (20.9 in).
A standard double roll is 33 ft (10.05 m). Check the label — it varies.
Printed on the label. 0 means a free match (random or plain) with no repeat waste.
10% covers a miscut, a damaged strip and a piece kept for repairs.
Whole rolls, including your extra-drop allowance.
- Drops (strips) needed
- 25Full-height strips around the room, before the extra allowance.
- Drops including extra
- 28
- Cut length per drop
- 105 inWall height + trim, rounded up to a whole pattern repeat.
- Usable drops per roll
- 3
- Wall area papered
- 339 ft²
- Waste per drop
- 8.6%Share of each cut strip thrown away to match the pattern and trim the ends.
- Wallpaper cost
- $0.00
Assumptions
- Drops are cut to a whole number of pattern repeats plus a trim allowance; a half-drop (offset) match may need an extra half repeat per strip.
- Doors are deducted at their full width and windows at half width, the usual trade convention.
- Roll dimensions come from the label — American 20.5 in × 33 ft and European 53 cm × 10.05 m are the common defaults.
| Repeat | Cut length per drop (in) | Drops per roll | Rolls for this job |
|---|---|---|---|
| Free match (0 in) | 100 | 3 | 10 |
| 6 in | 102 | 3 | 10 |
| 12 in | 108 | 3 | 10 |
| 18 in | 108 | 3 | 10 |
| 21 in | 105 | 3 | 10 |
| 24 in | 120 | 3 | 10 |
| 32 in | 128 | 3 | 10 |
| 36 in | 108 | 3 | 10 |
Same room, same roll — only the repeat changes. A big repeat can cost you a third more paper.
How this is worked out
The formula
Wall run = perimeter − door widths − ½ × window widths Drops = wall run ÷ roll width, rounded up Cut length = (wall height + trim), rounded up to a whole pattern repeat Drops per roll = ⌊roll length ÷ cut length⌋ Rolls = (drops × (1 + waste)) ÷ drops per roll, rounded up
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- What are you papering?
- Use total wall length for one feature wall, a hallway or a room with jogs.A room (four walls from length × width) · Total wall length (More options)
- Room length
- A number.in ft, in, m, cm · 0 or more · defaults to 12
- Room width
- A number.in ft, in, m, cm · 0 or more · defaults to 12
- Wall height
- Floor to ceiling, or to the picture rail if you stop there.in ft, in, m, cm · 0 or more · defaults to 8
- Roll width
- American rolls are 20.5 in (52 cm); European rolls 53 cm (20.9 in).in in, cm, m, ft · 1 or more · defaults to 20.5
- Roll length
- A standard double roll is 33 ft (10.05 m). Check the label — it varies.in ft, yd, m, in · 1 or more · defaults to 33
- Pattern repeat
- Printed on the label. 0 means a free match (random or plain) with no repeat waste.in in, cm, m · 0 or more · defaults to 21
- Extra drops for mistakes
- 10% covers a miscut, a damaged strip and a piece kept for repairs.a percentage · from 0 to 100 · defaults to 10
- Total wall length(under More options)
- Add up every wall you are papering.in ft, in, m, cm · 0 or more · defaults to 48
- Trim allowance per drop(under More options)
- 2 in top and bottom so you can slide the drop to match and trim it clean.in in, cm · 0 or more · defaults to 4
- Doors(under More options)
- A number.from 0 to 50 · whole numbers only · defaults to 1
- Width per door(under More options)
- Deducted in full — the short piece over a door comes out of offcuts.in in, cm, m, ft · 0 or more · defaults to 32
- Windows(under More options)
- A number.from 0 to 50 · whole numbers only · defaults to 2
- Width per window(under More options)
- Only half is deducted — you still paper above and below a window.in in, cm, m, ft · 0 or more · defaults to 36
- Price per roll(under More options)
- Leave 0 to skip the cost estimate.in dollars · 0 or more · defaults to 0
What you get back
- Rolls to buymain answer
- Whole rolls, including your extra-drop allowance.
- Drops (strips) needed
- Full-height strips around the room, before the extra allowance.
- Drops including extra
- Cut length per drop
- Wall height + trim, rounded up to a whole pattern repeat.
- Usable drops per roll
- Wall area papered
- Waste per drop
- Share of each cut strip thrown away to match the pattern and trim the ends.
- Wallpaper cost
What this assumes
- Drops are cut to a whole number of pattern repeats plus a trim allowance; a half-drop (offset) match may need an extra half repeat per strip.
- Doors are deducted at their full width and windows at half width, the usual trade convention.
- Roll dimensions come from the label — American 20.5 in × 33 ft and European 53 cm × 10.05 m are the common defaults.
About this calculator
Wallpaper is not sold by the square foot in any way that helps you. It comes on a roll of fixed width, and you hang it in full-height strips called drops. What matters is how many whole drops you can cut out of one roll — and that depends on the pattern repeat, not on your wall area.
How to use it
Enter the room size and the wall height, then copy the roll width, roll length and pattern repeat straight off the label. American rolls are 20.5 in wide and usually 33 ft long (sold as a "double roll"); European rolls are 53 cm × 10.05 m, which is almost the same thing. Set the repeat to 0 for a plain or free-match paper.
Doors are deducted in full — the short piece above a door comes out of offcuts. Windows are only deducted by half, because you still paper above and below them.
Why the repeat drives the waste
Every drop has to start at the same point in the pattern, so its cut length gets rounded up to a whole number of repeats. On an 8-ft wall you need 96 in of paper plus about 4 in of trim, so 100 in. With a 21-in repeat, five repeats is 105 in — you throw away 5 in of every strip. With a 36-in repeat, three repeats is 108 in, and now a 33-ft roll only gives you three drops instead of four.
That's the whole game: the repeat can quietly add 25–40% to the order without changing a single wall dimension. The table under the results runs your exact room against a range of repeats so you can see it. A half-drop (offset) match is worse still — the first drop of each pair starts half a repeat down the roll, which is why some manufacturers publish a longer "match length".
Reading the results
Rolls to buy is whole rolls including your extra allowance. Waste per drop is the share of each cut strip that goes in the bin. Usable drops per roll is the number to check against your own cutting plan — if it says three, and you were counting on four, that's where the extra roll came from.
Buy every roll in one batch and check that the batch (or "run") number matches. Colours drift between print runs, and a replacement roll bought a month later will show as a stripe on the wall. Order the extra now; keep the offcuts for repairs.
Frequently asked questions
▸How many rolls of wallpaper do I need for a 12 × 12 room?
With 8-ft walls, one door, two windows and a 21-in repeat, you need about 25 drops. A 33-ft roll gives three 105-in drops, so that's 10 rolls once you add 10% for mistakes.
▸Why does the pattern repeat matter so much?
Every drop has to be cut to a whole number of repeats so the pattern lines up. A 36-in repeat on a 100-in wall forces a 108-in cut, which can drop a 33-ft roll from four usable strips to three — a third more rolls for the same wall.
▸Should I subtract doors and windows?
Deduct doors in full and windows by half. You still hang paper above and below a window, and the piece over a door usually comes out of an offcut, so a full deduction for windows will leave you short.
▸What is a double roll?
US wallpaper is priced by the single roll but packaged as a double — one continuous 33-ft length instead of two 16.5-ft ones. Longer rolls waste less, which is why the trade sells them that way. Enter the length that's actually on the bolt.
▸How much extra should I buy?
10% is the normal allowance, and more if the paper has a large or half-drop repeat. Buy it all in the same batch number — colours drift between print runs, and a mismatched roll shows as a stripe.
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