A lineal yard, also known as a linear yard, can be misleading. Although it sounds like a single line or length, it is in fact a unit used to describe an object sold in length and width. For example, if a roll of wallpaper is 30 inches wide, a lineal yard would be a 36inch length of it, or 36 by 30 inches. Three lineal yards would be 108 by 30 inches of material. Carpet and wallpaper in the United States are sold by the lineal yard. To convert this to square feet, all you need is some simple math.

Find the width in inches of the lineal yard. For example, say it's 24 inches wide. Thus, a lineal yard of this material would be 36 by 24 inches.

Divide the width by 12:
24/12 = 2

Multiply the answer in Step 2 by 3. This will give you the square footage of the lineal yard:
2 x 3 = 6 square feet.
Tips & Warnings
 Always doublecheck the width of your lineal yard before converting.
References
 Photo Credit measurement image by Kimberly Reinick from Fotolia.com