Wallpaper Calculator

What is this calculator?

A wallpaper calculator turns wall measurements into a roll estimate before you order. Homeowners use it for bedrooms, powder rooms, feature walls, and living rooms where running short can be expensive because dye lots and patterns may not match later. It estimates base wall area, waste allowance, total required area, and rolls needed from the roll coverage you enter.

How does this calculator work?

Step 1: the calculator measures room perimeter from length and width, then multiplies by wall height. Step 2: it deducts door and window areas to get base wallpaper area. Step 3: it adds waste for trimming and pattern matching, then divides total required area by coverage per roll and rounds up to whole rolls.

Formula

Example Calculation

Example: A homeowner is papering a 12 ft x 14 ft room with 8 ft walls, one door, and two windows. Gross wall area is (12 + 14) x 2 x 8 = 416 sq ft. Deduct about 51.6 sq ft for openings, leaving 364.4 sq ft. With 10% waste, total required area is about 400.8 sq ft. If one roll covers 56 sq ft, 400.8 / 56 = 7.16, so the purchase rounds up to 8 rolls.

Common Mistakes

• Using floor area instead of wall area when estimating rolls.
• Ignoring pattern repeat or half-drop matches, which can increase waste.
• Ordering rolls in separate batches where dye lots may not match.
• Forgetting to deduct large doors and windows, then overbuying.
• Using advertised roll size instead of usable coverage after trimming.

Frequently Asked Questions