Wallpaper Calculator

What Is the Wallpaper Calculator?

Wallpaper has a consideration no other flooring or paint product does: pattern repeat. A patterned roll wastes extra material matching the pattern across seams between strips -- the bigger the repeat, the more waste -- while plain or non-repeating wallpaper doesn't have this problem at all. This calculator adds that allowance on top of a standard base waste factor.

How to Use This Calculator

Enter your wall area, your chosen roll's coverage in square feet, the pattern's repeat size in inches (enter 0 for plain/non-repeating wallpaper), and a base waste factor.

The Formula

This repeat-waste estimate is a common heuristic: repeats under about 6 inches add relatively little extra waste, while larger repeats (18-24in and up, common in bold patterns) add progressively more, capped at 25% since even very large repeats rarely justify more waste than that in practice.

Worked Example

Common Mistakes

• Ignoring pattern repeat entirely and using the same waste factor as plain wallpaper -- a large repeat can meaningfully increase the number of rolls needed.
• Not checking whether a roll's stated coverage already accounts for trimming -- some manufacturers list gross roll size rather than usable coverage.

Finding Roll Coverage and Pattern Repeat

Both numbers come from the product label or listing. Roll coverage is the usable area of a roll, and the repeat is the vertical distance between identical points in the pattern. Some wallpaper is sold in double rolls or by the yard, so check whether the coverage given is per single roll or per double roll, and make sure the wall area and roll coverage use the same units. A common mistake is entering the coverage of a double roll while ordering by single roll, which leads to buying half of what you need.

Worked Example With a Large Repeat

Suppose you are covering 300 square feet of wall with rolls that provide 30 square feet each, a pattern repeat of 24 inches, and a 10 percent base waste (hypothetical numbers). The repeat waste is 24 divided by 100, which is 24 percent, and it is under the 25 percent cap. The total waste is 34 percent. Rolls needed are 300 divided by 30, which is 10, times 1.34, or 13.4, so you would order 14. For a plain paper with no repeat, the same wall needs 11 rolls with only the base waste. The difference shows how much a large repeat can add.

Measuring Your Walls

• Multiply the wall height by the width of each wall to be papered, then add them together.
• Subtract large openings like doors and wide windows, though small ones are often left in because of the cuts around them.
• Measure height from the baseboard to the ceiling, or to the chair rail if you are papering only part of the wall.
• For a feature wall, measure just that wall and consider whether you want a larger allowance for a large repeat.

Drop Matches and Straight Matches

A straight match repeats at the same height across the seam, while a drop match shifts the pattern down by part of the repeat on each adjacent strip, so it uses more paper. This tool uses a single heuristic based on the repeat size, and it does not distinguish between them. If your paper has a drop match, consider a higher base waste, or ask the retailer how many rolls they recommend.

Interpreting the Result

The rolls figure is rounded up because you must buy whole rolls. Because wallpaper is printed in batches, buying all rolls at once from the same lot is important for a consistent color. Extra rolls may also be useful for repairs down the road, though returns policies for custom or printed paper are often strict, so ask before ordering.

Limits of the Estimate

The repeat allowance is an estimate, not an industry standard, and real waste depends on room height, layout, and the number of strips. Strip-based calculations, where you count how many strips fit in each roll, can be more precise for rooms with unusual heights. Confirm with the wallpaper supplier before ordering expensive paper.

Frequently Asked Questions