Wallpaper Calculator
Enter the distance around the room, the wall height and the size of your wallpaper roll to see how many strips and rolls you need. A pattern repeat is included because it uses extra paper.
How to use this wallpaper calculator
- Measure the width of each wall and add them together. Enter the total as the wall length.
- Enter the wall height from floor to ceiling.
- Enter the width and length of one roll from the label. Rolls are not always the same size.
- Enter the pattern repeat if the paper has a pattern that must match. Leave it at 0 for a plain or random pattern.
- Add a price per roll if you like, then press Calculate. The calculator rounds up to whole strips and whole rolls.
How to calculate how many rolls of wallpaper you need
Wallpaper is hung in vertical strips, so the calculator counts strips first and then how many fit in a roll.
- Strips = total wall length (in) / roll width (in), rounded up
- Strip length = wall height (in) + trim allowance, then rounded up to the next multiple of the pattern repeat
- Strips per roll = roll length (in) / strip length, rounded down
- Rolls = strips / strips per roll, rounded up
A pattern repeat can make each strip longer, so fewer strips fit in a roll.
Worked example
A room has 50 ft of wall that is 8 ft high. The wall length is 600 inches. With a 20.5 inch wide roll, the room needs 600 / 20.5 = 29.3, so 30 strips. Each strip is 96 inches plus 4 inches of trim, or 100 inches. A 33 ft roll is 396 inches, so it holds 396 / 100 = 3.96, which rounds down to 3 strips. You need 30 / 3 = 10 rolls.
With a 48 inch repeat, each strip is rounded up to 144 inches, so a roll holds only 2 strips and you need 15 rolls.
Assumptions & limits
- The walls are plain rectangles. Doors and windows are not deducted, so the result is a cautious estimate, and rolls can be saved by cutting around openings.
- The calculator uses whole strips because wallpaper is hung in full-height strips.
- Roll sizes vary by maker and country. A double roll or a European roll may be a different length, so enter your own size.
- The pattern repeat uses the simple method of rounding the strip up to a whole repeat. A drop match or an offset can need more paper.
- Buy all rolls from the same batch where you can, as color can differ between print runs.
Frequently asked questions
How do I calculate how many rolls of wallpaper I need?
Divide the total wall length by the roll width to get the number of strips, then divide by the strips you can cut from one roll. A 50 ft wall run with 20.5 inch rolls needs 30 strips.
How do I allow for a pattern repeat?
Round the strip length up to the next multiple of the repeat. A 100 inch strip with a 48 inch repeat becomes 144 inches.
Do I subtract doors and windows?
This calculator does not subtract them. That keeps the estimate on the safe side, because the paper above doors and below windows still needs full strips.
What size is a standard roll?
It varies. Always use the width and length printed on the roll you plan to buy.
Should I buy an extra roll?
Many people add a spare roll for mistakes and repairs. The strip count is already rounded up.
Can I use this for a feature wall?
Yes. Enter the width of that one wall as the wall length.
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Last updated: November 2026