How many rolls of wallpaper does a room need

What a roll of wallpaper actually covers before waste

Wallpaper sold in the United States is usually priced by the single roll but packaged as double rolls. A standard American double roll is about 20.5 inches wide and 33 feet long, which works out to roughly 56 square feet. European and metric rolls are commonly about 21 inches by 33 feet, around 57 square feet, sold as one bolt. Some designer papers and grasscloths come in wider or shorter bolts, so always read the label.

That 56 square foot figure is the paper on the roll, not what ends up on the wall. Every strip loses a few inches at top and bottom for trimming, and patterned papers lose more to matching. On a busy print with a big repeat, a double roll might only give you 40 square feet of finished wall. That gap is why square foot math on its own tends to leave people short.

How to measure a room for wallpaper the strip-by-strip way

Start with the perimeter. Measure the width of each wall you plan to paper and add them. Then measure the wall height from the top of the baseboard to the ceiling or crown molding, at a few points, and use the tallest number. Rooms in older Quincy houses are rarely square. Ceilings in a Wollaston two-family or a Wollaston Hill Victorian can vary half an inch or more across a room, and settled floors make the difference worse.

Next, divide the perimeter in inches by the roll width in inches, and round up. That gives you the number of strips. For a 12 by 14 foot bedroom, the perimeter is 52 feet, or 624 inches. Divided by 20.5, that's 30.4, so call it 31 strips. Doors and windows reduce this a little, but don't subtract them yet; partial strips over and under openings still use paper.

• Measure each wall width and add them for the perimeter
• Measure height in several spots and use the tallest
• Divide perimeter in inches by roll width, round up
• Note the pattern repeat and match type from the label

How pattern repeat changes the roll math

The pattern repeat is the vertical distance before the design starts over, printed on the label in inches or centimeters. Each strip has to start at the same point in the pattern so the design lines up across the wall. That means your cut length is the wall height plus a trim allowance, rounded up to the next full multiple of the repeat.

Using the same bedroom: walls are 8 feet, or 96 inches. Add 4 inches for trimming at top and bottom, and you get 100 inches. With a 21 inch repeat, the next multiple up is 105 inches, so every strip uses 105 inches of paper. A 396 inch double roll divided by 105 gives 3.77, and you can only use whole strips, so that's 3 strips per roll. Thirty-one strips divided by 3 is 10.3, which rounds up to 11 double rolls. Square foot math on the same room would have suggested 7 or 8.

Straight match versus half-drop match, and why it matters for roll count

A straight match means the pattern lines up straight across from strip to strip, at the same height. Every strip can be cut at the same point on the roll. A half-drop match means every other strip is shifted down by half the repeat, so the motif steps diagonally across the wall. Half-drop patterns are common on florals, trellis designs and many traditional papers.

With a half-drop, alternate strips start at a different spot on the roll, which usually wastes more paper. A simple way to plan for it is to add half the repeat to each cut length before figuring strips per roll. Some hangers work from two rolls at once, cutting odd strips from one and even strips from the other, to reduce waste. A random match or free match, like a plain texture or many grasscloths, has no repeat to align, so it wastes the least.

• Random or free match: lowest waste, cut to height plus trim
• Straight match: round cut length up to the full repeat
• Half-drop match: add about half a repeat per strip
• Large repeats over 24 inches: expect a lot of offcut

How much extra wallpaper to allow for waste and future repairs

Once you have a roll count from the strip method, add a margin. For a straight match or random match in a simple room, one extra double roll is usually enough. For a large repeat, a half-drop, or a room with many doors, windows, built-ins or a sloped ceiling, add 10 to 15 percent more. Dormers in South Quincy capes, the knee walls in converted Houghs Neck cottages and the tall stair halls in two-families all eat paper faster than flat walls.

Order everything from the same production run. Each run is printed with a batch or dye lot number, and colors can shift slightly between runs. Mixing lots can leave one wall slightly off from the rest. Keeping a spare roll from the same lot also means a water stain from an ice dam or a damaged corner can be patched later with paper that actually matches.

How to use our wallpaper roll calculator and when to have a paperhanger measure

Our wallpaper roll calculator runs the strip method for you. Enter the wall widths, ceiling height, roll width and length, and the repeat and match type from the label, and it returns the number of strips, strips per roll and a roll count with a waste allowance. It's a good check before ordering samples or comparing papers with different repeats.

For expensive papers, rooms with odd angles, stair halls or wallcoverings like grasscloth and murals, it's worth having the room measured in person before you order. A shortfall of one roll can mean waiting weeks for a new run that may not match. At walk-throughs in Quincy, Milton, Braintree and the rest of Norfolk County, our paperhangers measure the room, look at the paper you've chosen and give you a roll count with the layout in mind. Call (617) 576-8235 to arrange one.