Wallpaper Calculator

Things you may need

A quick list for the aisle. You may already own half of it.

• Wallpaper rolls
• Adhesive if needed
• Smoothing tool
• Seam roller
• Utility knife
• Level
• Sponge
• Drop cloth
• Primer or sizing if needed

How the estimate works

The calculator uses your measurements plus ordinary unit conversions. Editable fields handle the parts that change by product: waste, coverage, bag yield, box coverage, or material density.

The buy recommendation rounds up because stores do not sell half gallons, partial boxes, or a fraction of a bag.

• Wall length and height estimate wall area.
• Doors and windows reduce the area but do not remove all waste.
• Roll coverage and pattern waste convert area into rolls.
• Price per roll estimates the material cost before tools and paste.

Example: 30 linear feet of wall at 8 ft high

Thirty linear feet of wall at 8 ft high is 240 sq ft before openings. Subtract a 20 sq ft door and two 15 sq ft windows to get 190 sq ft. If a double roll gives about 56 usable sq ft, 190 divided by 56 is 3.4 rolls. With pattern waste, the safer shopping estimate is usually 4 or 5 rolls depending on the repeat.

Beginner notes

• Pattern repeats can increase waste.
• Check the roll coverage on the product listing.
• Order from the same batch or dye lot when possible.
• Measure wall height in several spots if the room is old or uneven.

Common mistakes

• Using advertised roll area when pattern matching reduces usable coverage.
• Ordering rolls from different dye lots.
• Subtracting every opening too aggressively and ending up short.
• Skipping wall prep when old paint, texture, or damage may show through.

Before you buy

• Find the roll width, roll length, and usable coverage from the product listing.
• Check pattern repeat and match type before deciding waste.
• Order an extra roll if the paper may be hard to match later.