It depends on your seam allowance, the thickness of your thread, the thickness of the quilt (type of batting, etc), any number of factors. I would probably just move the needle one spot to the right or left of center, whichever will solve the problem. I like to use my 1/4" foot to attach binding, and if it is a thin quilt, I cut my strips 1-7/8". If I want it a little thicker, I move the needle one spot to the left of center and cut my strips 2-1/4". I like it my binding to have an even width on the front and on the back. Sometimes you just have to take a few stitches, fold it around and see if it is going to work. If not, remove those stitches, adjust and start again.