How to use this calculator
- Add each wall receiving wallpaper.
- Enter the combined area of doors, windows, and other full openings.
- Enter the selected roll width and length.
- Choose waste and calculate whole rolls.
How the calculation works
Wall areas are combined and openings are deducted. Roll width and length determine nominal roll area. Waste applies to net wall area before the result is divided by roll area and rounded upward.
Formula
Net wall area = gross wall area − openings Roll area = roll width × roll length Purchase rolls = ceil(net area × (1 + waste %) ÷ roll area)
Worked example
Four 12 ft × 8 ft walls total 384 sq ft. After 50 sq ft of openings, 334 sq ft remain. A visible 20.5 in × 33 ft roll covers about 56.38 sq ft; with 10% waste, the estimate rounds to 7 rolls.
Project considerations
- Roll dimensions are visible and editable rather than assumed universal.
- The result uses nominal roll area and does not optimize strips or pattern repeats.
- Pattern matching, usable roll length, trimming, and manufacturer instructions can materially change quantity.
Frequently asked questions
Does this account for pattern repeat?
No. It provides transparent area-based planning and states that pattern-repeat optimization is excluded.
Should openings be deducted?
Enter only the combined opening area you intentionally want deducted; small openings may not reduce usable strips in practice.