To calculate the costs of wallpaper and labour on a worksheet, you will have to have some information. You will need the measurements of the area to be covered. The cost of the wallpaper will be a factor in the equation. It is important to know whether the wallpaper is a repeating pattern. Finally, you will need to know how much to charge, per roll, for the labour costs of installing the wallpaper.
Measure the length and width of the area you will be covering with the wallpaper. Multiply the length by the width to determine the square footage required. Multiply the sum by 15 per cent for waste, and add that to the original sum: (L x W) + (L x W x 15%) = square footage of wallpaper required. Divide that sum by the square footage contained on each roll of wallpaper to determine the number of rolls required.
Multiply the number of rolls required by the cost of the roll of wallpaper. Show your figures on the left side of the page so you can adjust easily if any factor changes. Place the resulting dollar amount in the right column under "Costs of Supplies."
Multiply the number of rolls by the cost of installation for each roll and, if applicable, for removal of old paper. Label the resulting sum "Labor." Place that dollar amount in the right column under the dollar amount for the cost of the wallpaper. Add the sums together. Add on any tax as required by your state. Total the amounts.
If the wallpaper has a pattern that you have to line up, you will need additional wallpaper because matching the patterns will likely take more than the 15 per cent waste calculated. You can find the square footage the roll will cover by determining the repeat length (the length of the pattern before it repeats) of the wallpaper by looking on the outside of the package for the repeat length or by measuring it yourself. On a 27 square foot roll of wallpaper with a the repeat length of 0 to 6 inches, the roll will only cover about 25 square foot. If the repeat length is 7 to 12 inches, the roll will only cover about 22 square foot; for a repeat length of 13 to 18 inches, it will cover 20 square foot; and for a repeat length of 19 to 23 inches, the roll will only cover about 18 square foot. Wallpaper is frequently sold in double rolls only. If that is the case, you should round up to the next even number of rolls for your calculations. Examples of the amounts charged for labour for removing or installing wallpaper, per roll, can be seen in the links contained in References and Resources.
It is better to overestimate the amount of wallpaper required for a job than to underestimate. Wallpaper should be purchased from the same lot number or it may not match properly. Extra wallpaper can be used for patches later.