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Wallpaper calculator

Wallpaper calculator

Wall perimeter and height, openings, roll size and pattern repeat: you get drops needed, drops per roll and rolls to buy.

Deterministic calculation in your browser. No signup to see the result.

Purchase quantity

9 roll

Net measurement: 32 m²

  • Wallpaper rolls9 roll
  • Drops (strips) needed25 unit
  • Drops per roll3 unit
  • Wallpaper paste (1 pack per 5 rolls)2 bundle

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How it's calculated (visible formula)

drop = height + repeat + 4 in; drops per roll = ⌊roll length ÷ drop⌋; drops = ceil((perimeter − openings ÷ height) ÷ width); rolls = ceil(drops ÷ drops per roll)

See methodology and formula versions

How to calculate it, step by step

  1. Measure wall perimeter and height.
  2. Subtract door and window openings.
  3. Check roll width, length and pattern repeat on the label.
  4. Work out drops needed and drops per roll.
  5. Divide and round up to rolls from one batch.

Worked example: 46 ft of wall, 8.2 ft high, 32 sq ft openings, 21 in × 33 ft rolls

  1. Drop ≈ 8.5 ft → 3 drops per roll
  2. ≈ 25 drops
  3. 25 ÷ 3 = 8.3

→ 9 rolls and 2 packs of paste.

Common mistakes

Pro tips

From calculation to quote

Add labour, overhead and your margin, and generate the professional PDF.

FAQs

How big is a roll of wallpaper?
US double rolls are about 20.5 in × 33 ft; European rolls 21 in × 33 ft (0.53 × 10.05 m).
What is pattern repeat?
The vertical distance before the pattern repeats; you lose paper matching it.
Should I buy extra?
Yes, one roll from the same batch for repairs.
Vinyl or non-woven wallpaper?
Non-woven is paste-the-wall and strips dry; vinyl is more washable.
Straight or drop match?
Straight matches at the same height; drop match is offset by half a repeat.
Can I wallpaper over textured walls?
Skim them smooth first or the texture will show.

Sources and standards

Maintained by · Formula v1.0.0 · Verified 2026-09-10 · Updated 2026-09-10 · Limits: quantity estimation, not structural design or site supervision.