42-43" is 1 1/6 of a yard. So each piece of a jelly roll is that long.
10 x 10 is 100 square inches. A yard of 42" is 1512 sq. inches, so about 15 layer cake pieces equals a yard. You can't cut 15 out of a yard---but for square inches that would be the count.
Charms are 5" square, right? so that is 25 square inches. 4 of these make one 10" x 10" so 60 of them equal one yard. Again you can't cut them that way, but--------------
Or do you want the info this way.
A yard of fabric would yield 14 strips of a jelly roll----perfect cutting ------with a dab left over.
A yard of fabric would yield 4 across and 3 down layer cakes (12)-------with about 6" left over.
A yard of fabric would yield 8 charms across and 7 down or 56 charms with a inch left over if you're perfect.
And of course, 4 FQ's make a yard.
ALL BASED ON 42" wide fabric.
Tell me how many pieces are in each and I'll tell you how many yards.