Learning to Sew—Determining Buttonhole Size
Ready made patterns have the buttonhole size already determined, but sometimes you want to use another size button or cannot find the button size called for in the pattern.
Measure your button by wrapping twill tape or seam binding around the button’s widest point and pinning the tape together. The button width will be half of this measurement.
To determine your buttonhole length, add ⅛” to the button width. If your buttons are thick add a little more than ⅛” to the length.