Wallpaper Calculator

Rolls are counted in drops, not in square feet. Strips needed = room perimeter / roll width, rounded up. Each strip covers the full height of the wall. Drop length = wall height + 4 inches of trim. If the paper has a repeat, that length is rounded up to a whole number of repeats, because a strip has to start at the same point in the pattern as the one beside it. A drop match adds another half repeat on average, since alternate strips start halfway along. Drops per roll = roll length / drop length, rounded down. The remainder is scrap. Rolls = strips needed / drops per roll, rounded up. That is why a large repeat costs rolls: an 8 foot wall with a 24 inch repeat needs a 9 foot drop, so a 33 foot roll gives three strips instead of four.

How many rolls of wallpaper do I need for a 12 by 14 room?

With 8 foot walls, that is 52 feet of perimeter and about 31 drops at 20.5 inches wide. A 33 foot roll with an 18 inch repeat gives 3 usable drops, so 11 rolls. The same room in a plain paper needs 8.

What is a pattern repeat and why does it matter?

The distance down the roll before the design starts again. Each strip has to begin at the same point in the pattern as its neighbor, so the paper is cut to whole repeats and the offcut at the top is thrown away. A big repeat can cost you 20 percent of the roll.

What is the difference between a straight match and a drop match?

On a straight match the pattern lines up at the same height across every strip. On a drop match every other strip is offset by half a repeat, so strips 1, 3 and 5 are identical and 2, 4 and 6 are the shifted version. A drop match wastes more paper and looks better on a large motif.

Should I deduct doors and windows?

Not from the roll count. Paper is hung straight past an opening and cut out afterward, so a window in the middle of a wall saves nothing. Only a very large opening, or a whole wall you are not papering, is worth taking out.

What is a single roll and a double roll?

American wallpaper is priced by the single roll and almost always sold as a double, which is one physical roll holding two singles. A double roll is around 33 feet long and 20.5 inches wide, so about 56 square feet. Check which one the price on the shelf refers to.

Why do all the rolls have to come from the same batch?

Ink is mixed per production run, and two batches of the same paper can be visibly different shades on the wall. The batch or dye lot number is printed on the label. Buy everything at once, including the spare.