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# How To Calculate Wallpaper

## What do I need to know when shopping for wallpaper?

1. Measure the width of each of the walls where you want to apply the wallpaper and add all measurements together (“Combined Width”).
2. Measure the height of all the walls.
3. Multiply the Combined Width by the height of the walls – this will give you the total square footage (“TSF”) of the wall space you need to cover with wallpaper. To keep it simple and to ensure that you have enough paper try to not make any deductions for doors, windows, cabinets, etc.
4. The final step is factoring in the repeating pattern. If the repeating pattern is 18″ or less then you must divide the TSF by 23, if the repeating pattern is 19″ to 25″ then divide the TSF by 20. This calculated number is the total number for single rolls of wallcovering that will be required for your project. If the pattern does not have a repeat, just random match, then just use the TSF from step 3 above.

When the dealer will calculate it for you.

A- If you are about to purchase wallpaper that has no repeating pattern, normally you will need only the total square footage of the surface that will be covered with wallpaper and the dealer should calculate the number of rolls you need to buy. This is the easiest way.

B- If you are about to purchase wallpaper with a repeating pattern you might need more than just the total square footage of the surface.  Depending on the width of the repeating pattern you might have to waste some wallpaper. So, in this case you will need to know the total length of the walls and the height of the ceiling (assuming that all walls have the same height) and the total square footage of the surface that is not being covered with wallpaper (doors, windows, etc.) so you can deduct that from the total square footage. This way the dealer will know the dimensions and will calculate how much you should order.

When you have to shop online or at a store that sells wallpaper, but won’t calculate it for you, you have to calculate it yourself.

Before buying you will need to keep in mind that things don’t always go as you wish, so you have to prepare for the worst. Mistakes can happen during installation, some types of wallpapers are easily damaged during installation, color of the print can slightly change from roll to roll, etc.  For these reasons ordering 10% extra is always recommended.

First we need to know that wallpaper is priced with single rolls and sold with double rolls. Here is where it gets confusing.

After calculating the total square footage of the wall or walls of the room (including doors and windows), then you can deduct the total square footage of doors and windows to get the total of the wallpaper square footage you need to order.

Allowing the pattern repeats to be calculated to the total square footage.

If the wallpaper has a pattern that repeats let’s say every 6 inches or less, the pattern repeat should not cause a problem unless you are ordering a very small amount of wallpaper and not allowing any extras.

If the pattern repeat is wider than 6 inches then divide the height of the wall by the number of inches of the pattern repeat and increase or round it off to the next highest number. For example, a 96” wall height divided by an 18” pattern repeat gives you 5.33 repeats, rounded off to 6.

Then, multiply the repeat measurement by the number of repeats you’ll need to determine the height figure you must use. In the case above, multiplying the 18” pattern repeat by 6 repeats tells you that you must calculate your wallpaper need according to the requirements of the 108” wall, rather than the actual 96” wall.

If you are not comfortable calculating the surface with this method, then just thing on ordering a few extra rolls just for this purpose. If it’s not a custom made wallpaper, most stores will accept returns, just remember to ask for their return policies before you purchase.

Wallpaper is usually packaged in double roll bolts.  Most double roll bolts of wallpaper are approximately 20.5” x 33’ (European metrics) containing 56 sq ft of paper, and some are 27” X 27′ (American double rolls) containing 70 sq ft of paper.  A bolt of wallpaper depending on the pattern contains about 40-50 sq ft of usable wallpaper.

Calculate the area of the walls that needs to be covered and divide the total square footage by the usable sq. ft. per bolt (about 40 sq. ft for largeest repeats of 20-24″ to as high as 50 sq. ft for smallest repeats of  less than 6″); then deduct ¼ bolt for each door or window that fully breaks a strip of wallpaper.

Example: To cover with wallpaper a wall 8′ high x 12′ long with a 20″ pattern repeat, first we must calculate the square footage of wall to be covered; 8′ x 12′ = 96 sq. ft. Allowing 40 sq. ft. per bolt, you would need 96 sq. ft. /40 usable sq. ft per bolt = 2.4 bolts, or, rounding up, three bolts of wallpaper.

How many rolls should I order?

Manufacturers and retail stores price the wallpaper by single roll. You might be required to purchase double rolls, meaning that if the price for a single roll is \$15 you will have to pay \$30, since a double roll will be the minimum to purchase. The prints and designs come in different width (varying from 21″-36″) and length (European and American), they have about the same usable square footage.

A standard single roll (American) contains 36 square feet of wallpaper with about 30 square feet of usable paper from each single roll you purchase.

An European single roll contains 29 square feet with about 25 square feet of usable paper for each single roll you purchase.