On the medium, 15 inch, wall decal you will get a complete set of smaller snowflakes (3 and 3/4 inch boxes); plus an set of the bottom row. On the wallpaper the boxes are 3 inches.
Wallpaper Coverage Calculator
Based on the dimensions you provide, this calculator will determine the number of custom-length sections of paper you'll need to cover any surface. If the height of your surface varies, input the tallest dimension in order for the pattern to line up correctly.
Enter your dimensions in feet (1 foot is 30.48 cm).