Wallpaper Calculator

The short answer

Wall area is perimeter times height, and a 12 by 14 foot room at 8 feet is about 416 square feet gross. A US roll typically covers 30 to 36 square feet, so that is 12 to 14 rolls before waste; a European roll covers about 57 to 60 square feet, so 7 to 8. Pattern repeat adds more than either figure suggests — a large repeat can add 20 to 30% over the plain area.

What it depends on

Roll size and repeat are the two variables that decide the order, and they must be checked before buying rather than after. The pattern match determines how much of each roll is lost to aligning the design, and a drop-match pattern loses more than a straight match. Openings are deducted but not fully, because paper still has to be cut and trimmed around them. Batch consistency matters as much as with paint.

Where this stops being useful

This is an area estimate. It does not cover lining paper, adhesive, sizing or the substrate preparation that usually decides the outcome, and wall condition affects consumption more than the area does. A retailer's measure and the product's stated coverage are authoritative for an order. General information and planning only, not engineering, structural or code advice.

The pattern repeat is the whole calculation. A wallpaper with a 20-inch repeat wastes considerably more than the area suggests, because every drop has to align with the one beside it. On a plain wallpaper, five percent waste is enough; on a heavy pattern it can be fifteen. Paste is part of the order too and is measured by area covered, not by drops used. And the wall width matters — a room wider than the paper width needs drops to be pieced together vertically, which is another seam and another waste.

Wallpaper is unforgiving in a way that paint is not. A seam that is off by a fraction shows, and on a patterned paper the repeat has to line up across the whole wall. Taking the time to work out the layout before the first drop is cut is what separates a finished room from a patched one.

Start at the most visible wall and work away from it, so the first wall is the one a viewer sees last and any pieced drop lands where furniture will cover it. Order all the paper for the room from one batch number, since colour shifts between batches are visible on a large flat surface. Paste the paper to the wall rather than to the backing in humid conditions — the backing can stretch and the seams will never quite close. Check the roll length as well as the width, because the two vary independently.

Wallpaper is bought in rolls, but a roll is a strip of fixed length and width, not a rectangle of wallpaper you can cut freely. That single fact explains why wallpaper estimates always seem to ask for more rolls than the wall area suggests: offcuts at the top and bottom of each drop, and the repeat of the pattern, waste material that cannot be used. Pattern repeat is the biggest source of waste. A plain paper can be hung almost without loss, but a large repeating pattern forces you to line up each drop, cutting away part of every strip to match its neighbour. The bigger the repeat and the shorter the roll, the more is thrown away — an allowance of ten to twenty per cent is typical, higher for a bold, widely spaced design. Drops are what really decide the count. You hang full-height strips from ceiling to floor, so the number of drops is the wall width divided by the roll width, rounded up, and each drop must be at least as long as the wall height plus the pattern offset. Calculating rolls from area alone is a reasonable approximation; calculating them from drop count is exact, which is why paper hangers measure the room, not the paint tin. This calculator takes your wall area, the coverage printed on the roll and a waste allowance for the pattern, then rounds up to whole rolls. It ignores doors and windows, which waste a little more, and assumes a standard roll. Measure the full wall run in a room, buy one extra roll if your pattern is bold, and keep the receipt in case you need a matching batch later.

This calculator returns estimates for planning and general information only. It is not engineering, architectural, structural, electrical or code advice, and it cannot replace a qualified professional who has seen the site. Material quantities depend on the actual dimensions, the product you buy and local building codes, so confirm the figures before ordering materials or starting work, and always follow local regulations.