Wallpaper Calculator
Find how many rolls of wallpaper to buy: enter the room size, the roll size and the pattern repeat. Advanced adds wall by wall, doors and windows, half-drop match, paste and cost.
Takes away one door and one window of a typical size. Advanced lets you set how many, their sizes and wall by wall.
About 5.33 m² per roll. Check the label on your roll.
Printed on the label, often 0–64 cm (0–25 in).
Half-drop adds about half a repeat to each drop.
Extra at the top and bottom to trim off. Typical: 10 cm (4 in).
For mistakes and later repairs, from the same batch.
A door or window only saves the drops that fit fully inside its width. The short pieces above and below are still cut.
Typical: one standard packet hangs about 5 standard rolls (25 m², 270 sq ft). Check the packet. Paste-the-wall papers use a different paste.
How your wallpaper is worked out
Decorators count drops, not square metres: drop length, drops per roll, drops round the room, then rolls.
- 1
Length of each drop
2.4 + 0.1 trim↑ to 53 cm repeat= 2.65 m
- 2
Drops per roll
10.05 ÷ 2.65= 3.79, round down= 3 drops per roll
- 3
Drops round the room
14 m ÷ 53 cm= 27, − 3 at openings= 24 full drops
- 4
Rolls to buy
24 ÷ 3 = 8 rolls5 short bits in offcuts+ 10% = 9 rolls
Read more: the formula, worked examples in metres and feet, typical roll sizes and tips
Wallpaper is sold by the roll, but it goes on the wall in full-height strips called drops. A roll only gives a whole number of drops, and with a pattern each drop has to start at the same point in the design. That is why decorators count drops instead of just dividing the wall area by the roll area. This calculator uses the same strip method, then fits the short pieces above doors and windows into the offcuts left at the end of each roll.
The formula
wall width = 2 × (length + width) for a whole room, or the width of one wall
drop length = height + trim, rounded up to a whole number of pattern repeats (+ half a repeat for a half-drop match)
drops per roll = roll length ÷ drop length, rounded down
drops across = wall width ÷ roll width, rounded up
full drops = drops across − drops that fit fully inside doors and windows
rolls = full drops ÷ drops per roll, rounded up, plus any short pieces that do not fit in the offcuts
rolls to buy = rolls × (1 + spare % ÷ 100), rounded up
paste packets = rolls to buy × roll area ÷ area one packet hangs, rounded up
Worked example
In metres. A room 4 m long, 3 m wide and 2.4 m high has a wall width of 2 × (4 + 3) = 14 m. With 10 cm trim, each drop needs 2.4 + 0.1 = 2.5 m. The pattern repeats every 53 cm, so round up to 5 repeats: 5 × 0.53 = 2.65 m per drop. A 10.05 m roll gives 10.05 ÷ 2.65 = 3.79, so 3 drops per roll, with 10.05 − 7.95 = 2.10 m left over. Going round the room takes 14 ÷ 0.53 = 26.4, so 27 drops. The 0.8 m door covers 1 whole drop and the 1.2 m window covers 2, so you need 24 full drops: 24 ÷ 3 = 8 rolls. The short pieces (one 0.53 m piece above the door, two 0.53 m above the window and two 1.06 m below it, each rounded to the repeat) all fit in the 2.10 m offcuts, so 8 rolls is enough. With 10% spare, 8 × 1.1 = 8.8, so buy 9 rolls. Wall area: 14 × 2.4 = 33.6 m², less the door (1.6 m²) and window (1.44 m²) = 30.56 m². Paste: 9 × 5.3265 = 47.94 m² ÷ 25 = 1.92, so 2 packets.
In feet and inches. A room 12 × 10 ft with 8 ft walls is 2 × (12 + 10) = 44 ft round. Each drop is 96 in + 4 in trim = 100 in, rounded up to 6 repeats of 18 in = 108 in (9 ft). A US double roll of 20.5 in × 33 ft (396 in) gives 396 ÷ 108 = 3.67, so 3 drops with 72 in left over. 44 ft = 528 in, and 528 ÷ 20.5 = 25.8, so 26 drops. A 3 ft door and a 3 ft window each cover 1 whole drop, leaving 24 full drops = 24 ÷ 3 = 8 double rolls. The short pieces (18 in above the door, 18 in above the window and 54 in below it) fit in the 72 in offcuts. With 10% spare, buy 9 double rolls (18 single rolls).
Why not just divide the area? 30.56 m² ÷ 5.33 m² per roll = 5.74, so an area-only calculator says 6 rolls. In real life the pattern repeat and the offcuts at the end of each roll mean you need 8. That is why we count drops.
Typical roll sizes
| Roll | Typical size | Area |
|---|---|---|
| UK and European standard | 0.53 m × 10.05 m (some brands 0.52 m) | about 5.3 m² (57 sq ft) |
| Wide | 0.70 m × 10.05 m | about 7.0 m² |
| Extra wide (non-woven) | 1.06 m × 10.05 m | about 10.7 m² |
| US double roll | 20.5 in × 33 ft | about 56 sq ft (5.2 m²) |
| US double roll, wide | 27 in × 27 ft | about 61 sq ft (5.6 m²) |
Typical sizes and rules of thumb, checked 11 October 2026. Brands differ, so use the size and repeat printed on your roll. The trim allowance (10 cm or 4 in per drop) and paste coverage (about 25 m², or 5 standard rolls, per packet) are common guides, not rules. US wallpaper is often priced per single roll but sold in double rolls. The wall drawing places doors and windows evenly along the wall as an example.
Tips
- Check every roll has the same batch number. Shades can change slightly between batches.
- Hang the first drop against a plumb line, not a corner. Corners are rarely straight.
- Large patterns look best centred on a chimney breast or feature wall, which can mean an extra drop.
Common questions
How many rolls of wallpaper do I need?
Work out how long each drop is (wall height plus trim, rounded up to the pattern repeat), how many drops one roll gives, and how many drops fit around the room. A 4 × 3 m room 2.4 m high with a 0.53 × 10.05 m roll and a 53 cm repeat needs 24 full drops at 3 per roll, so 8 rolls, or 9 with 10% spare.
What is a drop of wallpaper?
A drop is one full-height strip of wallpaper, cut from the roll to fit the wall from ceiling to skirting. Decorators count drops, not square metres, because each roll only gives a whole number of drops. The bit left at the end of a roll is often too short for another full drop.
How does the pattern repeat change the number of rolls?
Each drop must start at the same point in the pattern, so its length is rounded up to a whole number of repeats. With a 2.4 m wall, 10 cm trim and a 53 cm repeat, each drop is 2.65 m instead of 2.5 m, so a 10.05 m roll gives 3 drops instead of 4. A half-drop match adds about half a repeat more to each drop.
What is the difference between straight match and half-drop match?
In a straight match the pattern lines up straight across from one drop to the next. In a half-drop match every second drop is moved down by half a repeat, so the pattern runs diagonally. Half-drop papers waste a little more, so they usually need more rolls. Free match papers, like plain or striped ones, have no pattern to line up.
How big is a roll of wallpaper?
A typical UK and European roll is 0.53 m wide and 10.05 m long, about 5.3 m². Wide rolls of 0.70 m and 1.06 m are common too. In the US, wallpaper is usually sold in double rolls, for example 20.5 in × 33 ft, about 56 sq ft. Always check the size on the label.
Should I buy an extra roll of wallpaper?
Yes, it is wise to buy a spare. Rolls are printed in batches, and a new batch can be a slightly different shade. Buying all rolls with the same batch number at once, plus one or two spare, means you can fix mistakes or damage later with paper that matches.
Related calculators
Made by Zulu Calculator, part of AlphaZulu LLC. Formulas are shown in full and rule figures are checked against official sources; see how we build calculators.