If you’re getting ready to purchase wallpaper, and you’re trying to figure out how much you’ll need, you can calculate the square footage of your wall space, and then go from there.
Residential wallpaper, with the exception of grasscloth, manufactured for the U.S. typically comes in two widths: 20.50 inches and 27 inches. Single and double rolls of 20.50” width paper are usually 16.5’ long and 33’ long, respectively. While single and double rolls of 27” width paper are usually 13.5’ long and 27’ long, respectively.
Depending on the wallpaper sheet width, a double roll covers 57 to 61 square feet, while a single roll is 29 to 31 square feet. Remember, wallpaper only comes in double rolls, even though they price out the cost in single roll quantities.
You can count on double rolls to always be twice as long as single rolls. Double rolls give you more coverage, since you can get up to three eight foot drops out of a double roll, as opposed to just one with a single roll. So, purchasing in double roll format works out better for you anyway. If you’ve purchased say... 8 rolls, you’ll actually see 4 rolls that are double in size in your order. So just keep this in mind when picking up your order or when opening your delivery.
The following is the square footage you can get out of each double roll BEFORE the repeat is taken into account:
Knowing how much to order also depends on whether the wallpaper pattern is random match, or if the pattern repeats. Random match wallpaper, like vertical lines, requires no special consideration when hanging. If a double roll has 56 sq.ft of coverage then you will get that exact amount. Patterns with a repeat though, need to be lined up properly, and you could lose up to half the roll, in waste, doing so.
Each pattern of wallpaper has its own repeat length, but most are between 1 to 24 inches. You can usually find this number in the product description field if you’re purchasing online. Or it can be found on the back of the wallpaper book if you’re shopping in store. You’ll need to keep this number in mind when you’re deciding how much to order. The repeat needs to be factored in or you will not have enough paper to complete the room.
Figuring out the exact number of rolls you need may sometimes be tricky. You’ll want to make sure you get that number right the first time to ensure all your wallpaper comes from the same lot — for consistency in color and pattern. A good idea is to double check your measurement numbers with an online wallpaper calculator tool or speak with a representative in store.
A good rule of thumb to go by that always works is to to take your square footage and divide by 21. That will give you the amount of single rolls you need and then just round up to the nearest even number. Doing that will make sure you account for any human error, mistakes and future replacement should the wallpaper tear.