The rule of thumb is that a well-placed buttonhole/button is that when the button is sewn onto the center front line, there will be a space between the edge of the button to the edge of the garment half the diameter of the button.
Sounds complicated, huh ... it is not. If your overlap is the same measurement as the width of the button, half the button will use up half of the overlap and the amount left over will be just right.
SO -- choose your button at the design stage so you can request the correct amount of overlap OR make sure you use a button the size that you drafted.
Maximize your visual results by attention to little details
