Wallpaper Calculator – How Many Rolls You Need
Wallpaper can change a plain room into a warm, finished space in a single weekend. The hard part is buying the right amount — too little leaves a wall bare, and too much wastes money.
Wallpaper Calculator
A standard roll is 20.5 inches wide and 33 feet long. Enter 0 for the repeat if your paper is plain or has no repeat. Each strip includes 4 inches of trim.
The secret is measuring the wall before you shop, not guessing at the shop.
Pattern repeat changes everything, because each strip must start at the same point in the pattern.
This free wallpaper calculator works out how many strips you need, how long each strip must be, and how many rolls to buy.
A standard roll is 20.5 inches wide and 33 feet long, so the calculator works from the real roll size.
It also adds 4 inches of trim to every strip, so you can cut each one cleanly at the top and bottom.
How to Use This Calculator
Example
Let us paper one wall that is 12 feet long and 8 feet high, using paper with a 12 inch pattern repeat.
First, the strips. The wall is 144 inches long, and each strip is 20.5 inches wide.
Divide 144 by 20.5 to get 7.02, and round up to 8 strips.
Next, the strip length. Add the 8 foot height, the 12 inch repeat as 1 foot, and 4 inches of trim as 0.33 feet.
Each strip must be 9.33 feet long. Eight strips need 74.7 feet of paper in total.
One roll holds 33 feet, so divide 74.7 by 33 to get 2.26, and round up to 3 rolls.
With no repeat, each strip is 8.33 feet long, the total is 66.7 feet, and the answer is still 3 rolls.
Always round up, never down. A part strip still needs a full strip of paper, and a part roll still needs a whole roll.
Measure twice before you order. A wrong length wastes money, while a short order leaves a wall half finished.
For a whole room, add the lengths of all four walls together and enter that total as the wall length.
This example uses one wall, but the same steps work for a whole room.
The Bottom Line
Wallpaper looks best when every strip lines up and nothing runs short halfway up the wall.
Measure the walls, check the repeat, and let the calculator do the maths before you buy.
Buy the rolls the calculator gives you, and keep one spare roll for future repairs or a bad cut.
A spare roll from the same batch matches perfectly, while a later batch can differ slightly in shade.
Start with the longest wall, keep your strips in order, and save every offcut until the room is done.
Good measuring turns a scary job into a calm one, and the calculator keeps the numbers honest.
When the last strip is up, step back and enjoy the room — you measured well, and it shows.
Frequently Asked Questions
What is pattern repeat?
Pattern repeat is the distance before the design starts again down the roll. Each strip must be cut so the pattern lines up at the same point, which uses extra paper.
Why do I add 4 inches of trim?
The extra 4 inches lets you trim each strip neatly at the ceiling and the skirting. Walls are rarely perfectly straight, so the spare length covers small uneven spots.
What if my paper has no repeat?
Enter 0 for the repeat, and the calculator will add only the trim. Plain paper and random designs need no matching, so you use less paper per strip.
How do I measure a room with doors and windows?
Measure the full wall length and ignore doors and windows. The spare paper covers the cuts around them, and the offcuts often paper the narrow spaces above doors.
Can I use this calculator for inches?
Yes. Enter the wall length and height in feet, and the repeat in inches. To convert inches to feet, divide by 12, so 96 inches is 8 feet.
Should I buy an extra roll?
Yes, one spare roll is wise, especially with a large repeat. It covers bad cuts and future repairs, and the same batch always matches your walls.
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