I think it depends. All that I have purchased has been a tighter weave like the fabric for the top. That said, I have seen some that is "flimsy". The wear of a quilt, it seems to me, would be the back as that is where the friction would be from having it on a bed and using it. Why, then, would you want flimsier fabric on the back to wear and abrade much quicker? But then, I have seen "flimsy" fabric for the top as well and I don't buy it. At least I hope my theory is mostly correct. I have used some beautiful batik that was purchased for the back of one quilt in the front of another.