Wallpaper Strip Counter

Wallpaper strip calculation determines how many vertical strips are needed to cover a wall from baseboard to ceiling, and how many strips can be cut from one standard roll, accounting for pattern matching.

Strips per wall formula: Number of Strips = Wall Width (inches) ÷ Wallpaper Width (inches) Round up to the nearest whole number.

Strips per roll formula: Strips per Roll = Usable Roll Length ÷ Strip Length

Where Usable Roll Length = Total Roll Length − Waste at Roll Ends

Strip length (with pattern repeat): Strip Length = Ceiling Height + Pattern Repeat (Each new strip must be started at the right point in the pattern to align horizontally)

Rolls needed: Rolls Needed = Total Strips Needed ÷ Strips per Roll Always round up — never down. Add 1 extra roll as a safety buffer.

What each variable means:

• Wallpaper width — standard rolls: 20.5–27 inches wide (US); 53 cm (European)
• Roll length — standard US roll: 33 feet (396 inches). European bolt: 10 meters (393 inches).
• Pattern repeat — the vertical distance before the design repeats. Random-match or straight-match patterns waste less. Drop-match patterns (where alternate strips are offset) waste more.
  • No repeat (textured/solid): 0 inches wasted per strip
  • Small repeat (under 6 in): waste 3–6 in per strip
  • Large repeat (18–24 in): waste 12–18 in per strip

Reference: standard wallpaper coverage

• Single roll covers ≈ 28–35 sq ft (after trim and pattern matching waste)
• Double roll covers ≈ 56–70 sq ft

Worked example: Room wall: 12 ft wide × 9 ft tall. Wallpaper: 20.5 in wide, 33 ft roll, 18-inch pattern repeat.

Strips needed = (12 × 12 inches) ÷ 20.5 = 144 ÷ 20.5 = 7.02 → 8 strips

Strip length = 108 in ceiling height + 18 in repeat = 126 inches per strip

Strips per roll = 396 in ÷ 126 in = 3.14 → 3 strips per roll

Rolls needed = 8 ÷ 3 = 2.67 → 3 rolls (plus 1 buffer roll = buy 4 rolls)