Copy & pasted this from an e-mail I received today (Aboutquilting.com)
While We're Talking About Binding<Q>
</Q><CITE>© Janet Wickell</CITE>
One of my biggest binding pet peeves concerns the binding instructions that many quilting authors have traditionally written. I've cautioned quilters on this since I began writing quilting books in the 1990s, but still see incorrect instructions everywhere.
[h=3]The Real Deal[/h]
When preparing to miter binding at the corner of a quilt, the point where you should stop and backstitch must be a distance equal to the finished width of the binding.
Nearly all patterns tell you to stop 1/4" away from the quilt's edge. That's correct
if you are sewing a 1/4" finished width binding, and that width is a must if quilt blocks surround the outer edges of the quilt, since they have a built-in 1/4" seam. What if you have a border, where the width of binding is arbitrary? I've made lots of miniature quilts with 1/8" bindings, and larger quilts with 1/2" bindings. Try stopping 1/4" from the edge of those quilts and you'll end up with a messy (if not impossible to construct) mitered corner. Stop sewing at the point that matches your finished binding width and the miter will create itself, almost automatically.