Wallpaper Calculator
Calculate how many wallpaper rolls you need for a room.
Accounts for pattern repeat, doors, and windows.
Calculating wallpaper correctly prevents costly shortages or excess. Wallpaper is sold in rolls with standard dimensions that vary by region and manufacturer.
Standard roll sizes:
- US standard single roll: 27 inches wide × 27 feet long (about 60.75 sq ft)
- US double roll: 27 inches wide × 54 feet long (about 121.5 sq ft) — most common retail packaging
- Euro roll: 20.5 inches wide × 33 feet long (about 56.4 sq ft)
Basic calculation:
- Calculate total wall area: (Room perimeter × Wall height)
- Subtract openings: doors (~21 sq ft each) and windows (~15 sq ft each)
- Divide net wall area by usable coverage per roll
Pattern repeat is the most overlooked factor. If the wallpaper has a pattern that repeats every 12 inches, you may waste up to 12 inches per strip aligning the pattern. The larger the repeat, the more waste you generate.
Waste factor by pattern type:
- No pattern / random match: ~10% waste
- Straight match (small repeat, under 6"): ~15% waste
- Straight match (large repeat, 12"+): ~25% waste
- Drop match: ~20-30% waste
Always buy extra. Order at least 1-2 extra rolls beyond the calculated amount. Wallpaper dye lots can vary, so rolls from different batches may not match perfectly. Having extra from the same batch ensures you can make repairs later.
Pro tip: If buying from a store, confirm their return policy on unopened rolls.