Wallpaper Calculator

Room perimeter, wall height, roll size and pattern repeat to rolls needed.

Your estimate

Results update as you type. Round up when ordering.

Based on a standard US double roll, 20.5 in × 33 ft. Check the label.

  • Formula checked against manufacturer specs
  • Rounded up to whole units
  • Runs in your browser

The strip method

Square-foot estimates often come up short because of pattern matching. Instead, work in strips: strips needed = wall width ÷ roll width; each strip's length = wall height + pattern repeat; strips per roll = roll length ÷ strip length (round down). Rolls = strips ÷ strips per roll, rounded up.

Example: 48 ft of wall, 8 ft high, 20.5 in × 33 ft rolls, no repeat: 576 ÷ 20.5 = 28.1 → 29 strips; 396 ÷ 96 = 4 strips per roll; 29 ÷ 4 = 7.25 → 8 rolls.

Single vs. double rolls

U.S. wallpaper is often priced per single roll but sold in double rolls; European rolls are commonly 0.53 × 10 m. Enter the actual length of what you buy.

Tips

Buy all rolls from the same batch/lot number and one extra roll for mistakes. Doors and windows aren't subtracted here; the leftover usually covers above-door pieces.

✓ Formula reviewed and tested · Updated Oct 2026

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FAQ

How accurate is the wallpaper calculator?

It uses the standard formula shown on this page and rounds bags, boxes and pieces up to whole units. Product sizes vary by brand, so confirm with the label or your supplier before you buy.

Should I buy extra material?

Yes. A 5–10% allowance covers cuts, spills and uneven surfaces; running short mid-job usually costs more than a few leftovers.

Is this calculator free?

Yes. Every PorchMath calculator is free, needs no account and runs entirely in your browser.