Wallpaper Calculator
Enter your room dimensions and wallpaper specs to find out exactly how many rolls you need — with pattern repeat, door and window deductions, and a 10% waste allowance automatically included.
Please enter valid room length, width, and ceiling height values greater than 0.
How to Use This Calculator
- Measure your room. Record the length, width, and ceiling height in feet. Measure at the longest points and use the tallest wall height if your room is irregular.
- Count doors and windows. Enter the number of standard doors and windows. The calculator automatically subtracts their approximate area from your total to avoid over-ordering.
- Enter your roll dimensions. Check the product label for exact roll width and single-roll length. US standard rolls are 20.5" × 16.5 ft; European rolls are often 21" × 33 ft (sold as a double roll).
- Select the pattern repeat. The pattern repeat is printed on the wallpaper label. If the paper has no repeat (solids, subtle textures), choose "No repeat." Larger repeats waste more material and require more rolls.
- Review your roll count. The result already includes a 10% waste buffer. Round up when purchasing — leftover rolls can be saved for repairs.
How Wallpaper Quantities Are Calculated
- Wall area:
2 × (length + width) × height − (doors × 21 sq ft) − (windows × 15 sq ft) - Drop height (with pattern):
ceil(ceiling height ÷ pattern repeat) × pattern repeat inches - Strips per roll:
floor((roll length in inches) ÷ drop height) - Strips needed:
ceil(room perimeter in inches ÷ roll width in inches) - Rolls needed:
ceil(strips needed ÷ strips per roll) × 1.10, rounded up to whole number
Pro Tips
- [object Object]
- [object Object]
- [object Object]
- [object Object]
Recommended Products for This Project
Roman Pro-838 Heavy Duty Wallpaper Adhesive
Professional-grade clear paste for all wallpaper types.
View on Amazon →Shur-Line Wallpaper Smoothing Brush
Wide brush for bubble-free paper application.
View on Amazon →Hyde Tools Wallpaper Scoring Tool
Perforates existing wallpaper for easy removal.
View on Amazon →Gardz Problem Surface Sealer — Quart
Primer-sealer for repaired and skim-coated walls.
View on Amazon →Frequently Asked Questions
How do I account for pattern repeat in my wallpaper order?
Pattern repeat means each strip must be cut so the pattern aligns horizontally across the wall. If you have a 9-inch repeat and 9-foot walls, each strip must be cut from a length of roughly 110 inches (the next multiple of 9 above 108) instead of exactly 108 inches. This wastes 2 inches per strip, which can add up significantly. This calculator automatically rounds up each strip length to the next full repeat, giving you an accurate roll count.
Should I subtract wall area for doors and windows?
Yes, but only modestly. This calculator subtracts approximately 21 sq ft per door (a standard 32" × 80" opening) and 15 sq ft per window (an average 30" × 60" opening). Because strips must still be cut and run past openings to maintain pattern alignment, the actual material savings are less than the raw opening area. The 10% waste factor built into the total accounts for this.
What is the standard wallpaper roll size in the US?
The most common US wallpaper roll is 20.5 inches wide and 16.5 feet long (a single roll). Many wallpapers are sold as double rolls — 20.5 inches wide and 33 feet long — packaged as one unit. European wallpaper is commonly 21 inches wide and 33 feet long. Always check the product label for exact roll dimensions before ordering.
Can I hang wallpaper over existing wallpaper?
It is generally not recommended. Existing wallpaper that is peeling, bubbling, or multiple layers thick will not provide a stable substrate and the added moisture from new adhesive can cause both layers to fail. If the existing wallpaper is firmly bonded, single-layered, and in good condition, some professionals will hang over it, but the safer and more durable approach is to strip, skim-coat any damage, and prime the bare wall before hanging.