This calculator estimates how many rolls of wallpaper you need based on your room's perimeter and wall height.
The method
Calculate total strips needed: Perimeter × 12 ÷ Roll Width (converts feet to inches).
Calculate strips per roll: Roll Length ÷ (Wall Height × 12)
Rolls needed: Strips ÷ Strips per Roll (rounded up).
Step-by-step
Measure your room's perimeter (total length of all walls) in feet.
Enter the wall height in feet.
Check your wallpaper roll label for width and length (defaults: 21" wide, 396" long — standard US double roll).
Worked example
Room perimeter: 48 ft. Wall height: 8 ft. Standard roll (21" × 396"). Strips = 48 × 12 ÷ 21 ≈ 28. Strips per roll = 396 ÷ 96 ≈ 4. Rolls = 28 ÷ 4 = 7 rolls.
Tips
Buy one extra roll for mistakes and future repairs. Pattern repeats (large designs that must line up) increase waste — add 10–15% more. Always check the dye lot number to ensure color consistency across rolls.