Wallpaper Calculator — HomeCalcPro

🖼️ Wallpaper Calculator

Room Length (ft)

Room Width (ft)

Wall Height (ft)

Roll Length (ft)

Roll Width (inches)

Pattern Repeat (inches)

Number of Doors

Number of Windows

📊 Wallpaper Needed

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Wallpaper Hanging Tips

Always buy 10–15% extra — dye lots can vary and discontinued patterns are hard to match later.
Start in an inconspicuous corner and work toward your focal wall.
Use a plumb line to ensure your first strip is perfectly vertical.
Soak paste wallpaper for the manufacturer's recommended time before hanging.
Keep windows closed for 24–48 hours after hanging to allow uniform drying.

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How to Use This Calculator

Measure your room's length and width in feet, and the wall height from floor to ceiling.
Enter your wallpaper roll dimensions — check the label for roll length (typically 27 ft) and width (typically 21 inches). These vary by brand and country of origin.
Select the pattern repeat if your wallpaper has a repeating design. This is listed on the wallpaper label as "pattern repeat" in inches.
Input the number of doors and windows — the calculator deducts 21 sq ft per door and 15 sq ft per window from total wall area.
The result shows exact rolls needed and rolls with a 12% buffer. Always buy the buffered amount — dye lots cannot be matched after the fact.

The Formula Explained

Strips per Roll = Roll Length ÷ Usable Drop Height | Total Strips = Perimeter ÷ Roll Width | Rolls = Total Strips ÷ Strips per Roll × 1.12

The "usable drop height" accounts for pattern repeat waste — for a 12-inch pattern repeat on a 9-foot wall, each strip must start at a repeat boundary, so the effective cut length per strip is 9 ft plus up to 12 inches of waste. A single roll typically yields 2–4 strips depending on wall height and pattern repeat. The 12% buffer covers strips wasted on inside and outside corners and the inevitable mismatched cut.

Material Buying Guide

Wallpaper types vary widely in durability, installation method, and ease of removal:

Peel-and-Stick Wallpaper: Self-adhesive, repositionable, and removable without damage — ideal for renters or accent walls. Limited pattern selection; not suitable for textured walls. Typically 20.5 inches wide × 18 ft per roll.
Paste-the-Wall Wallpaper (Non-Woven): The modern standard. Paste goes on the wall, not the paper — no soaking or booking required. Installs faster and removes cleanly in sheets without steaming. Most European wallpapers use this format.
Traditional Paste-the-Paper: Paste is applied to the back of each strip, which must then "book" (fold paste-to-paste) for 3–5 minutes before hanging. More difficult for beginners but offers a wider range of patterns and textures.
Grasscloth and Natural Fiber: Textured, organic look — bamboo, jute, seagrass. Must be dry-hung (no water-based paste on the face). Seams show prominently — this is considered normal. Not suitable for humid rooms.
Paste and Tools: Budget one bucket of paste per 3–4 rolls. You'll also need: a smoothing brush or plastic smoother, a sharp utility knife with fresh blades, a seam roller, a plumb bob or level, and a trough for pasting (if paste-the-paper type).

Frequently Asked Questions

How much extra wallpaper should I buy?

Always buy at least 10–15% extra beyond your calculated roll count. With a large pattern repeat (18 inches or more), buy 20% extra. Save at least one full roll after installation — if a strip is damaged in 5 years, you'll need it. Dye lots change between production runs, making an exact color match impossible from new stock.

Do I need to prime the walls before wallpapering?

Yes — apply a wallpaper primer (also called a sizing) before hanging. It seals the drywall so paste doesn't soak in unevenly, creates a consistent surface for adhesion, and allows for easier removal later. Never hang wallpaper directly over fresh paint that hasn't fully cured (wait at least 30 days).

How do I remove old wallpaper?

Score the wallpaper with a scoring tool, then apply a removal solution (fabric softener + water, or commercial DIF) and let it soak for 10–15 minutes. Peel in large sections from top to bottom. A wallpaper steamer makes the job much faster for stubborn old paste. Expect to take 1–2 days for a full room, followed by 1 day of wall repair before you can repaper.

Can I wallpaper over textured walls?

Heavily textured walls (orange peel, knockdown) show through most wallpapers and prevent proper adhesion. You'll need to skim coat the walls smooth first, let dry, sand, and prime. Peel-and-stick wallpaper does not work on textured walls at all — the adhesive won't bond properly to raised texture.

What is a pattern repeat and why does it matter?

A pattern repeat is the vertical distance before the pattern starts over. When hanging multiple strips, each strip must align with the same point in the pattern — so you waste the overhang above the match point. A 24-inch repeat wastes an average of 12 inches per strip. On a room requiring 20 strips, that's 20 extra feet of wallpaper wasted — roughly one extra roll.

🏗️ Pro Tip: Wallpaper with a pattern repeat requires significantly more material than solid wallpaper — add the full repeat distance to your per-drop calculation. A 24-inch repeat on an 8-foot wall wastes an average of 18 inches per strip. Always order from the same dye lot: color variations between lots become obvious when rolls hang side by side. Order one extra roll and save it for repairs.