I think you are worrying about the width being too much to just cover the seam. If you cut the binding 2 1/2" and fold it in half that is 1/1/4". Take a 1/4" seam X 2 = 1/2". Then fold over 1/4" seam X 2 = 1/2". That leaves 1/4" extra. You would divide that by 2 = 1/8" to play with. I have never had a problem with having too wide of a binding. If you are worried, cut your binding 2" which is what I used to do.