Find out how many rolls of wallpaper you need for a room — accounting for pattern repeat, openings, and roll size.
Strips per roll
3
Total strips
28
Calculator
Rolls needed
10
Strips per roll
3
Total strips needed
28
Straight-match vs. drop-match
Straight match (0 in repeat)
10
How to estimate wallpaper rolls
First work out how many strips you need: divide the room perimeter (sum of all wall widths) by the roll width to get the number of strips. Round up to a whole number — partial strips still use a full strip from the roll.
Then find how many strips one roll yields: divide the roll length by the strip height. If your wallpaper has a pattern repeat, each strip needs one extra repeat of material to align with its neighbour, so add the repeat to the strip height before dividing. Finally divide total strips by strips per roll and round up for whole rolls to buy.
What is a pattern repeat?
Pattern repeat is the vertical distance before the design repeats itself. For a drop match or offset match, each new strip must be shifted down by half a repeat, which wastes material. The calculator adds one full repeat of waste per strip.
How much extra should I buy?
The calculator already rounds up to whole rolls, which gives a small buffer. For patterned wallpaper or rooms with awkward angles, consider buying one extra roll to cover mistakes and to keep a matching batch for future touch-ups.
Should I deduct doors and windows?
Yes — the openings deduction field lets you subtract the total area of doors and windows. Multiply each door height by width, do the same for windows, and enter the combined total. The calculator converts that area to equivalent strips and removes them from the count.
Results are estimates. Verify with a professional for important decisions.
About this calculator
This calculator tells you exactly how many wallpaper rolls to buy for a room, including extra material lost to pattern-repeat alignment. Use it before any decorating project where you need to avoid running short mid-job or over-ordering an expensive patterned paper.
How to read your results
The headline figure is the total number of rolls to purchase. The bar chart beneath compares rolls needed with no pattern repeat (straight match) against rolls needed with your actual repeat (drop match), so you can see at a glance how much the pattern design adds to the order. Supporting stats show strips per roll and total strips required.
Worked example
Room 10 ft × 10 ft (40 ft perimeter), 8 ft walls, rolls 21 in wide × 27 ft long, 24 in pattern repeat.
The 24 in repeat reduces each roll from 3 usable strips to 2 (each strip needs 10 ft of roll length to align, leaving only 27 ft ÷ 10 ft = 2 strips). With 23 strips needed across the perimeter, the order rises from 8 rolls (no repeat) to 12 rolls — 4 extra rolls consumed by pattern waste.
Frequently asked questions
What is pattern repeat and why does it matter?
Pattern repeat is the vertical distance before a motif restarts on the wallpaper. When hanging adjacent strips, each strip must be shifted to align the pattern, wasting part of the roll. A larger repeat wastes more material per strip and therefore increases the number of rolls needed.
Should I enter a perimeter or room dimensions?
For a standard rectangular room enter the length and width and the calculator derives the perimeter automatically. Use the perimeter mode if the room has an unusual shape — just measure along each wall and add the lengths together.
How do I deduct doors and windows?
Enter the total area of openings (doors, windows) in square feet in the openings field. The calculator converts that area into whole strips and subtracts them from the strip count before calculating rolls.
Why should I buy more rolls than the exact result?
Professional decorators recommend adding one or two rolls as a buffer for cutting errors, future repairs, or dye-lot variation between print runs. If the result is not a round number the calculator already rounds up to the next full roll.
What roll dimensions should I use?
Standard European double rolls are typically 20–21 in wide and 33 ft long. US single rolls are commonly 27 in wide and 15 ft long. Check the label on the roll you plan to buy and enter those figures for an accurate estimate.
How it's calculated
The number of strips required is the ceiling of wall perimeter divided by roll width. Each strip must be cut long enough to cover wall height plus one full pattern-repeat increment so that the design lines up with the adjacent strip; strip length equals wall height plus pattern repeat in feet. Strips per roll is the floor of roll length divided by strip length. Total rolls is the ceiling of net strips (after deducting opening strips) divided by strips per roll. The formula follows the method published by Inch Calculator and the strip-waste approach described by WallCover.
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