You asked the question, but I don't know if you really want an answer. How many quilts depends of course on the size and complexity of the quilt. Let's say that one quilt, together with backing and binding, takes 20 yards. (Not enough for a large complex quilt but more than needed for a smaller simple quilt - somewhere in the middle!) Okay, your 500 yards would only make 25 quilts. Now it doesn't sound like so much, does it? Now you need to go out and buy more!!!