Wallpaper Calculator

How It Works

Wallpaper is sold by the roll, but walls are measured in square feet — so the job is one division. The calculator subtracts doors and windows from your total wall area, divides what is left by the usable coverage of one roll, and rounds up to whole rolls. Running short mid-wall is the one mistake you cannot fix cheaply.

The key number is usable coverage, not the gross figure on the packet. A standard US roll covers about 57 square feet gross, but pattern matching and trimming eat into that — every strip must be cut so the pattern lines up, and the offcuts are wasted. Fifty square feet per roll is a safe planning figure; use less for a large pattern repeat.

Worked Example

Walls totalling 460 sq ft, minus 60 sq ft of doors and windows, leave 400 sq ft to paper. At 50 sq ft per roll, that is 400 ÷ 50 = 8 rolls exactly. If a large pattern repeat drops usable coverage to 40 sq ft per roll, the same room needs 400 ÷ 40 = 10 rolls — the pattern decides the order as much as the room does.

Assumptions

• Coverage is the usable figure per roll after pattern matching — not the gross figure on the packet.
• Walls are measured as flat rectangles; alcoves and slopes need measuring separately.

Rolls needed at different coverages (net wall area after openings):

How to Use This Calculator

Measure each wall (length × height), add the areas, and enter the total. Subtract the doors and windows, and set the usable coverage per roll — start with 50 sq ft unless your roll states otherwise. The result updates live.

Tips and Practical Advice

Buy all rolls from the same batch: colour can vary slightly between batches, and a mid-wall change is visible. If your pattern has a large repeat, buy one extra roll beyond the calculation — pattern waste is the most common reason paperers run short. And keep the leftover strips: a torn section later is a quick patch if you still have matching paper.