Wallpaper Calculator

Wallpaper is bought by the roll but hung in full-height strips, so the honest way to estimate is to count strips, not just area. Work out how many standard rolls you need for a whole room or a single wall, allowing for the pattern repeat and a waste margin, and see the wall area, strips needed, drops per roll and the material cost — so you buy enough from one batch and avoid a mid-job mismatch.

%
$
Rolls needed — standard rolls
Wall area — sq ft
Strips needed — with waste
Drops per roll — strips per roll
Estimated cost — materials

How to Calculate Wallpaper

Pick room or wall, enter the roll details, and read the rolls.

1

Choose room or wall

Use Room to enter the length, width and wall height and let the calculator work out the perimeter for you, or Wall size to enter a single run of wall directly by its width and height.

2

Enter the roll and pattern

Set the roll length and width from your wallpaper's label, the pattern repeat in inches, and a waste allowance. A standard roll is about 33 ft long and 20.5 in wide — roughly 10 m by 53 cm.

3

Read rolls, strips and cost

You get the number of standard rolls to buy, the wall area, how many full-height strips you need and how many you get per roll, plus — with a price per roll — the material cost.

Frequently Asked Questions

How many rolls of wallpaper do I need for a room?
Start by measuring the room's perimeter — add the length and width of the room and double it — then multiply by the wall height to get the wall area. A standard roll of wallpaper covers roughly 30 square feet once you allow for trimming, but the honest way to count is by strips, not area, because you cannot split a strip across two lengths. This calculator divides the wall perimeter by the roll width to find how many vertical strips you need, works out how many full-height strips you get from one roll, and divides one into the other to give whole rolls. A small room with 40 feet of perimeter and 9 foot walls usually needs about four to six rolls depending on the pattern repeat and how much waste you allow.
What is a pattern repeat and why does it matter?
A pattern repeat is the vertical distance before the design starts again, and it matters because you have to line the pattern up where one strip meets the next. To match the pattern you often waste a length of paper at the top of each strip so the motif lines up with the strip beside it, which means a patterned wallpaper covers less wall per roll than a plain one. The larger the repeat, the more you waste. This calculator adds one full pattern repeat to the length of every strip, so a big repeat lowers how many strips you get from a roll and pushes the roll count up. Set the repeat to zero for a plain paper or a random match, and enter the stated repeat in inches for a patterned one.
What is the standard wallpaper roll size?
Most wallpaper is sold in standard rolls that are about 10 metres long and 53 centimetres wide, which is roughly 33 feet by 21 inches, giving around 56 square feet of paper before any trimming or pattern matching. In practice a standard roll covers closer to 25 to 30 square feet of wall once you allow for waste at the top and bottom of each strip and for matching the pattern. American rolls are sometimes sold in double or triple rolls but priced as one, so always check the length and width printed on the label rather than assuming. Enter the actual roll length and width from your wallpaper into the calculator so the strip and roll counts match the paper you are buying.
How do I measure my walls for wallpaper?
Measure the width of every wall you want to paper along the floor and add them together to get the total distance around the room, then measure the height from the top of the skirting to the ceiling. For a whole room you can multiply nothing — simply add the room length and width and double the result to get the perimeter quickly. Do not subtract small doors and windows, because the offcuts around them rarely make up a full strip and it is safer to have a little spare, but you can leave out a very large opening such as a patio door. Enter your measurements in feet or metres using the unit selector, and the calculator turns them into strips and whole rolls for you.
How much extra wallpaper should I add for waste and matching?
A waste allowance of around ten percent is sensible for most jobs, covering trimming at the top and bottom of each strip, the odd mistake, and short offcuts you cannot reuse. Increase it toward fifteen or twenty percent for a wallpaper with a large pattern repeat, for rooms with many windows and doors where lots of part-strips are cut, or if you are new to hanging paper. It is also worth keeping one spare roll from the same batch for future repairs, because dye lots vary and a later roll may not match exactly. This calculator adds your chosen waste percentage to the number of strips before working out rolls, so the figure it gives already includes a margin for matching and mistakes.

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