Wallpaper Amount Calculator

Wallpaper calculations require knowing your wall area, the roll dimensions, and the pattern repeat distance. Getting this wrong means either running short mid-project or buying too many expensive rolls.

Standard roll sizes:

• US standard single roll: 27 inches wide × 13.5 feet long = 30.4 sq ft (usable: ~25 sq ft after trimming)
• US double roll: 27 inches wide × 27 feet long = 60.75 sq ft (usable: ~50 sq ft)
• European standard: 20.5 inches wide × 33 feet long = 56.4 sq ft (usable: ~46 sq ft)

This calculator works from the usable figure of 50 sq ft per double roll and adds one spare roll on top, so it deliberately comes out higher than a calculation run against the nominal 60.75. The gap is the trimming allowance plus the spare. If you would rather enter your own roll coverage and skip the spare, use the Wallpaper Calculator.

Pattern repeat types:

• Random/no match: no pattern alignment needed, so the least waste, around 10%.
• Straight match: the pattern aligns at the same height on each strip. Figure 15%.
• Drop match: the pattern aligns at half the repeat distance. The most waste, 25% or more on a large repeat.

The formula:

1. Calculate total wall area: Perimeter × Height
2. Subtract openings: Doors (21 sq ft each) + Windows (15 sq ft each)
3. Divide net area by usable coverage per roll
4. Add waste factor for pattern matching
5. Round up to next whole roll

Pattern repeat impact: A 24-inch (61 cm) pattern repeat on an 8-foot wall means you lose up to 24 inches per strip in alignment waste. Smaller repeats (under 12 inches) waste less.

Buying tips:

• Always buy from the same dye lot (batch number) to ensure consistent color
• Buy 1–2 extra rolls beyond the calculation for mistakes, repairs, and future patches
• Most stores allow returns of unopened rolls within 30–60 days
• Measure twice, order once. Running short mid-project means waiting on new stock, and the new stock may not match.

Tip: Wallpaper is sold as single rolls but usually packaged as double rolls. Always confirm with your retailer whether the roll length listed is single or double before calculating.