CalcLibrary

Wallpaper Calculator

Estimate how many wallpaper rolls you need for a rectangular room. Enter room dimensions, your roll spec (width, length, pattern repeat), and door/window counts to get rolls to buy, strips needed, and total wall area — works for European 0.53 m × 10 m rolls and US 27 in × 27 ft double rolls alike.

Units
m
m
m
cm
m
cm
%
Examples

A 4 m × 3.5 m bedroom, 2.5 m ceiling, 0.53 m × 10 m roll with a 64 cm pattern repeat, 1 door, 2 windows.

Rolls to Buy (with waste)
10
Strips Needed
27
Total Wall Area
37.5 m²
Effective Coverage per Roll
4.07 m²

Order 11 rolls — one extra on top of the calculation — so dye-lot mismatches don’t leave you short.

Pattern-repeat math is approximate — actual waste depends on the drop-match style (straight match, half-drop, random match). The calculator assumes straight-match worst case for one repeat unit. Order one extra roll for dye-lot consistency: if you run short, the next batch may not match.

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Examples

How It Works

Formula

P=2 (L+W)P = 2\,(L + W)

hs={⌈H/r⌉⋅rr>0Hr=0h_s = \begin{cases} \lceil H / r \rceil \cdot r & r > 0 \\ H & r = 0 \end{cases}

sr=⌊Lr/hs⌋s_r = \lfloor L_r / h_s \rfloor

sf=⌈P/wr⌉s_f = \lceil P / w_r \rceil

a=min⁡ ⁣(⌊D+0.5 Wn⌋, ⌊sf/4⌋)a = \min\!\left(\lfloor D + 0{.}5\,W_n \rfloor,\ \lfloor s_f / 4 \rfloor\right)

Ns=max⁡(0, sf−a)N_s = \max(0,\ s_f - a)

N=⌈⌈Ns/sr⌉⋅(1+w/100)⌉N = \lceil \lceil N_s / s_r \rceil \cdot (1 + w/100) \rceil

Variables

LL

Room length(m)

WW

Room width(m)

HH

Ceiling height(m)

PP

Wall perimeter(m)

rr

Pattern repeat (0 for plain)(m)

hsh_s

Strip height including repeat snap(m)

LrL_r

Roll length(m)

wrw_r

Roll width(m)

srs_r

Strips per roll (rounded down)

sfs_f

Full strips around the room (rounded up)

DD

Number of doors

WnW_n

Number of windows

aa

Opening allowance (capped)

NsN_s

Strips actually needed

ww

Waste allowance(%)

NN

Rolls to buy (rounded up, with waste)

The calculator finds the room perimeter (2 × (L + W)), multiplies by ceiling height to get total wall area, then sizes each strip. With a pattern repeat the strip height is rounded UP to the next repeat unit so the pattern matches across strips; without a repeat the strip equals the ceiling height. It divides roll length by strip height (rounded down) to get strips per roll, divides perimeter by roll width (rounded up) to get strips needed, subtracts a heuristic opening allowance (one strip per door, half per window, capped at a quarter of the wall), divides to get rolls, and adds the waste %. Order one extra roll on top of that for dye-lot consistency.

Frequently Asked Questions

01How many rolls of wallpaper do I really need?
Enter your room dimensions, the roll size you plan to buy (European 0.53 m × 10 m and US 27 in × 27 ft double rolls are common), and the pattern repeat. The calculator returns the rolls-to-buy figure including a waste allowance. Order one extra roll on top of that for dye-lot consistency — if you run short, the next batch may not match.
02What is a pattern repeat and why does it matter?
The pattern repeat is the vertical distance between identical points in the design. To match the pattern across strips, each strip is cut up to a full repeat unit longer than the ceiling height — paper that ends up as off-cut. Bigger repeats = more waste per strip. Plain (non-repeating) wallpaper has a repeat of 0.
03Should I order an extra roll?
Yes — plan on one extra roll on top of the calculator’s estimate for dye-lot consistency. Wallpaper is dyed in batches; rolls printed in different batches can have visibly different shades, even when the pattern is identical. The extra roll is also useful for repairs years down the line.
04How are doors and windows handled?
The calculator subtracts roughly one strip per door and half a strip per window from the strips-needed count. The allowance is capped at a quarter of the wall so a small room with many openings doesn’t over-subtract. A door or window that spans more than one strip-width still saves at most one strip’s worth of paper — the off-cuts rarely line up cleanly.
05Does it work for European and US roll sizes?
Yes. Roll width and roll length are both inputs, so any spec works — European single rolls (0.53 m × 10 m), US American double rolls (27 in × 27 ft), commercial wide rolls, and custom sizes. Switch the units toggle to enter feet/inches; everything is computed internally in metres.

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