Wallpaper Calculator
Wallpaper is not an area calculation. Decorators count drops (the number of full-height strips the walls need), and then work out how many drops each roll yields once the pattern repeat is allowed for. This calculator does it that way, which is why it is more accurate than dividing square metres.
Your measurements
Check your order
Before ordering roll materials
- Compare usable roll width and length with the cutting plan, not just the total area.
- Check pattern, direction and matching requirements before combining offcuts.
- Confirm the backing, permitted adhesive or fixing method, and suitable cutting tools.
Tools for this job
Measure wall heights and allow for pattern matching before cutting drops. Use a sharp, suitable blade when trimming edges.
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- Score and trim suitable sheet materials
Utility knife
STANLEY Classic 99 retractable utility knives
For scoring or trimming sheet materials that allow knife cutting. Choose a blade suited to the material and support the work on a cutting surface.
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Short tape measure
STANLEY 25-foot tape measure
For checking lengths, widths and short runs before ordering. This is a 25-foot tape; use matching units in the calculator and check the scale on the selected model.
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Why the drop method beats dividing square metres
A standard European roll is 10.05 m long and 53 cm wide, which is 5.3 m² of paper. Divide a 40 m² room by 5.3 and you get 7.5 rolls. But you cannot use a roll like that: each strip has to run the full height of the wall, and whatever is left at the end of the roll is too short to use.
With 2.5 m walls, each drop needs 2.6 m of paper including trim, so a 10.05 m roll gives 3 drops and 2.25 m of waste. That is 22% lost before you even consider the pattern. The drop method captures this; an area calculation does not.
The formula
Where drop length = wall height + 10 cm trim, rounded up to a whole number of pattern repeats when the paper has one.
Worked example
A 5 m x 4 m room, 2.5 m high, one door and one window, plain paper on standard 10.05 m x 53 cm rolls.
Wall width = 2 × (5 + 4) = 18 m. Deduct 0.9 m for the door and 0.27 m for the window = 16.8 m. Drops = 16.8 ÷ 0.53 = 32 drops. Drop length = 2.5 + 0.1 = 2.6 m, so each roll gives 10.05 ÷ 2.6 = 3.8, rounded down to 3 drops. Rolls = 32 ÷ 3 = 10.7, rounded up to 11 rolls.
Now add a 52 cm pattern repeat: 2.6 m is exactly five repeats, so the drop length and roll count stay unchanged. With a 64 cm repeat the drop rounds up to 3.2 m, each roll still yields 3 drops, and you waste 0.6 m per drop. Large repeats can push you into an extra roll very quickly.
Standard roll sizes
In the US, wallpaper is priced per single roll but almost always packaged and sold as a double roll. Choose the double-roll option so the drops-per-roll figure is right.
| Roll type | Length | Width | Area |
|---|---|---|---|
| European standard | 10.05 m | 53 cm | 5.3 m² |
| US single roll | 5.5 m (18 ft) | 68.6 cm (27 in) | 3.8 m² (40 sq ft) |
| US double roll | 11 m (36 ft) | 68.6 cm (27 in) | 7.5 m² (81 sq ft) |
| Wide non-woven | 10 m | 70 cm | 7.0 m² |
| Extra wide / contract | 25 m | 106 cm | 26.5 m² |
Pattern repeat: the hidden cost
- Free match / plain: no repeat, minimum waste. Every drop is exactly the wall height plus trim.
- Straight match: the pattern lines up horizontally across the seam. Each drop must be cut to a whole number of repeats, so you lose up to one repeat per drop.
- Offset / half-drop match: alternate drops start half a repeat down. The waste is similar to a straight match, but you should buy one extra roll because you cannot always cut consecutive drops from the same roll.
- As a rule, add one roll for any repeat over 50 cm, and one extra for a half-drop pattern.
Do not deduct windows and doors too aggressively
It is tempting to subtract the full area of every opening, but you still paper above a door and above and below a window, and those short pieces rarely come from the offcuts. This calculator deducts a full 0.9 m of wall width per door and only half a drop per window, which matches how decorators estimate.
For a feature wall, switch to I know the total wall width and enter just that wall.
Sources and assumptions
Rolls are counted from complete drops that fit the wall height and selected pattern repeat, rather than simply dividing wall area by roll area.
- Graham & Brown: measuring for wallpaper: The manufacturer explains why wall measurements, match type and pattern repeat affect roll quantities, including offset patterns.
Before using this estimate
- Deductions for doors and windows are approximations. Pieces above and below openings still need the correct pattern alignment.
- Murals, unusually large repeats and complex offset patterns need a wall-by-wall cutting plan. Check actual roll width, length, repeat and batch before ordering.
Source notes reviewed . See how we check calculations and handle corrections.
Planning your order
Check the inputs before buying: measure the surfaces you need, then apply an allowance and round to whole packs. The guides include worked examples you can follow alongside this calculator.
Published by OrderEnough. This is a planning estimate: check the product specification and the assumptions above before ordering. Last updated . Read how we source our figures on the methodology page.