How to calculate wallpaper
Wallpaper is estimated by area, then adjusted for the waste created when matching patterns:
Rolls = (wall area − openings) × (1 + waste %) ÷ coverage per roll
Wall area is the room perimeter times the wall height: 2 × (length + width) × height. We subtract roughly 21 sq ft per door and 15 sq ft per window, add a pattern allowance, then divide by the usable coverage of a roll and round up.
Single vs. double rolls
| Roll type | Typical usable coverage |
|---|---|
| Single roll | ~25 sq ft |
| Double roll (one bolt) | ~50–56 sq ft |
| Euro roll (10 m) | ~28–30 sq ft |
Always use the figure on your product's label — usable coverage is lower than the raw roll size once you account for trimming.
Tips
- Mind the repeat. Large patterns waste more at each strip — add up to 20%.
- Buy the same batch. Check that all rolls share a batch (lot) number so colors match.
- Keep a spare roll. Useful for repairs and for papering a later accent wall.