How to work out how many rolls of wallpaper you need
Dividing the wall area by the area of one roll looks simple, but it undercounts. Wallpaper goes up in vertical strips, and the piece left at the end of a roll is often too short for another full strip. Professionals count strips instead: how many strips cover the walls, and how many whole strips you can cut from one roll.
Example in metric: a room of 4 by 3.5 m has 15 m of wall. With a standard European roll 0.53 m wide, 15 ÷ 0.53 = 28.3, so you need 29 strips. The walls are 2.5 m high and the paper has a 53 cm straight repeat, so each strip is cut at 2.5 + 0.53 + 0.10 = 3.13 m. A 10.05 m roll gives 10.05 ÷ 3.13 = 3.2, so 3 strips per roll, and 29 ÷ 3 = 9.7 means 10 rolls. You end up with 1 spare strip and an offcut of about 0.66 m on each roll.
The same in US units: a 12 by 14 ft room has 52 ft (624 in) of wall. With a 20.5 in double roll that is 624 ÷ 20.5 = 30.4, so 31 strips. On 8 ft walls with a 21 in repeat each strip is 96 + 21 + 4 = 121 in, a 33 ft (396 in) double roll gives 3 strips, and 31 ÷ 3 = 10.3 means 11 double rolls.
Rolls for common room sizes
US double rolls of 20.5 in × 33 ft, 4 in trim per strip, no doors taken off:
| Room | Wall length | Strips | 8 ft, random | 8 ft, 21 in repeat | 9 ft, random | 9 ft, 21 in repeat |
|---|---|---|---|---|---|---|
| 10 × 10 ft | 40 ft | 24 | 8 | 8 | 8 | 12 |
| 10 × 12 ft | 44 ft | 26 | 9 | 9 | 9 | 13 |
| 12 × 12 ft | 48 ft | 29 | 10 | 10 | 10 | 15 |
| 12 × 14 ft | 52 ft | 31 | 11 | 11 | 11 | 16 |
| 14 × 16 ft | 60 ft | 36 | 12 | 12 | 12 | 18 |
European rolls of 0.53 × 10.05 m, 10 cm trim per strip:
| Room | Wall length | Strips | 2.5 m, random | 2.5 m, 64 cm repeat | 2.7 m, random | 2.7 m, 64 cm repeat |
|---|---|---|---|---|---|---|
| 3 × 3 m | 12 m | 23 | 8 | 8 | 8 | 12 |
| 3 × 4 m | 14 m | 27 | 9 | 9 | 9 | 14 |
| 4 × 3.5 m | 15 m | 29 | 10 | 10 | 10 | 15 |
| 4 × 5 m | 18 m | 34 | 12 | 12 | 12 | 17 |
| 5 × 6 m | 22 m | 42 | 14 | 14 | 14 | 21 |
The tables show how the wall height and the repeat work together. On 8 ft walls a 21 in repeat costs nothing extra, because 3 strips fit on a double roll either way. On 9 ft walls the same repeat leaves room for only 2 strips per roll, and you need about half as many rolls again. The metric rolls behave the same way at 2.7 m with a 64 cm repeat.
Wallpaper roll sizes
- European standard roll: typically 0.53 m wide and 10.05 m long, about 5.3 square meters. Sold and priced per roll.
- European wide roll: typically 0.70 m × 10.05 m, about 7 square meters. Fewer seams, heavier to hang.
- US double roll: commonly 20.5 in × 33 ft, about 56 sq ft. In the US, wallpaper is usually priced per single roll but sold only in double rolls, so a price of $40 per single roll means $80 per roll you take home.
- US single roll: typically rated at about 36 sq ft, with about 27 sq ft usable after trimming and matching. Some wider papers come as 27 in × 27 ft double rolls.
Pick a preset or enter a custom roll width and length from the label. The calculator shows double rolls for the US presets and can price them per single roll.
Pattern repeat and match
The pattern repeat is the vertical distance after which the design starts over. It is printed on the label, typically 21 in (53 cm) or 64 cm (25 in) for larger designs. The match type tells you how neighboring strips line up:
- Random match: stripes, textures and plain papers line up anywhere, so no repeat is added.
- Straight match: the design continues at the same height on every strip. Each strip gets one full repeat extra, so you can cut it at the same point of the pattern.
- Half-drop match: every second strip is shifted down by half a repeat. That may need half a repeat extra per strip, so the calculator adds one and a half repeats. In the metric example above this raises the cut length to 3.40 m, only 2 strips fit on a roll and the count goes from 10 to 15 rolls.
The trim allowance is the extra you cut off at the ceiling and the baseboard: about 2 in or 5 cm at the top and the same at the bottom, 4 in or 10 cm per strip in total.
Doors, windows and spare rolls
Be conservative with openings. A standard door about 3 ft (0.9 m) wide covers one full strip width of every common roll, so the calculator takes one strip off per door you enter. A patio door or a wide built-in closet can count as two. Windows are not deducted, because you still paper above and below them and the pattern has to carry on. The short pieces above doors and windows usually come from the offcuts at the end of each roll.
A spare roll costs little compared to running out. Rolls from a later print run can differ slightly in color, so buy everything with the same batch or lot number at once and keep the spare for repairs.
How to use the wallpaper calculator
- 1Choose US or metric units, then enter the length and width of the room. For an accent wall or a few separate walls, switch to single walls and enter the width of each.
- 2Enter the wall height from floor to ceiling and the number of doors you will paper around.
- 3Pick the roll size and the match type from the label, and enter the pattern repeat. Use random match for papers without a repeat.
- 4Read the strips needed, strips per roll and rolls to buy. Tick the spare roll and add the price per roll or per single roll to see the total cost.
Frequently asked questions
How many rolls of wallpaper do I need for a 12 x 12 room?
A 12 by 12 ft room has 48 ft of wall. With 20.5 in wide US double rolls that is 29 strips. On 8 ft walls with a 21 in pattern repeat, each 33 ft double roll gives 3 strips, so you need 10 double rolls. With 9 ft walls only 2 strips fit on a roll and the count goes up to 15 double rolls.
How many strips do I get from one roll of wallpaper?
Divide the roll length by the cut length of one strip and round down. A European roll of 10.05 m gives 3 strips on a 2.5 m wall with a random match (2.60 m per strip), but only 2 strips on a 2.7 m wall with a 64 cm repeat (3.44 m per strip). A 33 ft US double roll gives 3 strips on 8 ft walls and 2 strips on 9 ft walls with a 21 in repeat.
What does pattern repeat mean on wallpaper?
It is the height after which the design starts over, printed on the roll label. Typical repeats are 21 in (53 cm) and 64 cm (25 in). For a straight match, add one full repeat to every strip so each one can start at the same point of the design. A half-drop match can need half a repeat more. Random match papers like stripes or plain textures have no repeat to add.
Do you subtract doors and windows when measuring for wallpaper?
Only large openings, and only in whole strips. A standard door about 3 ft (0.9 m) wide saves one full strip of any common roll width. Windows are usually not taken off, because the wall above and below still needs paper and the pattern has to continue across. Many pros do not subtract anything, which leaves a little extra for mistakes.
How big is a double roll of wallpaper?
A common US double roll is 20.5 in wide and 33 ft long, about 56 sq ft. Wallpaper in the US is usually priced per single roll but sold only in double rolls. A single roll is typically rated at about 36 sq ft, of which about 27 sq ft is usable after trimming and matching. European rolls are sold one at a time and are typically 0.53 by 10.05 m, about 5.3 square meters.