Calcolatore Rotoli di Carta da Parati — Formula
## How to Calculate Wallpaper Rolls
### Formula
**Net Wall Area = (Perimeter x Height) - Openings Area**
**Usable Coverage per Roll = Roll Length x (Roll Width / 12) x Efficiency**
**Rolls Needed = ceil(Net Wall Area / Usable Coverage per Roll)**
Efficiency is typically 90% for solid or random patterns and 80% for patterns with a repeating motif. The repeat causes waste because each strip must be aligned to the pattern.
### Standard Roll Sizes
American single rolls: 21 in wide x 33 ft long (about 57 sq ft gross). European rolls: 21 in wide x 33 ft long. Double rolls are twice the length.
### Formula
**Net Wall Area = (Perimeter x Height) - Openings Area**
**Usable Coverage per Roll = Roll Length x (Roll Width / 12) x Efficiency**
**Rolls Needed = ceil(Net Wall Area / Usable Coverage per Roll)**
Efficiency is typically 90% for solid or random patterns and 80% for patterns with a repeating motif. The repeat causes waste because each strip must be aligned to the pattern.
### Standard Roll Sizes
American single rolls: 21 in wide x 33 ft long (about 57 sq ft gross). European rolls: 21 in wide x 33 ft long. Double rolls are twice the length.
Esempio Risolto
A room with 52 ft perimeter, 8 ft ceilings, 40 sq ft of openings, standard 21-inch rolls at 33 ft, no pattern repeat.
- Gross wall area = 52 x 8 = 416 sq ft
- Net area = 416 - 40 = 376 sq ft
- Coverage per roll = 33 x (21/12) x 0.90 = 51.97 sq ft
- Rolls needed = ceil(376 / 51.97) = 8 rolls