Button diameter + button depth.

Button diameter + button depth.

• A. Pocket size
• B. Zipper length
• C. Needle gauge
• D. Buttonhole formula

Answer: (D)

Sizing a buttonhole comes from the button you plan to use. The button’s diameter and its depth (thickness) tell you how big the hole must be so the button can pass through without being too loose or too tight. The buttonhole formula is the standard method for turning those measurements into a hole length that fits the button's shape and still works with the garment. The other options aren’t about how large a buttonhole should be: pocket size, zipper length, and needle gauge relate to other features or sewing decisions, not to determining the buttonhole size. So using the buttonhole formula to compute the opening length is the correct approach.

Sizing a buttonhole comes from the button you plan to use. The button’s diameter and its depth (thickness) tell you how big the hole must be so the button can pass through without being too loose or too tight. The buttonhole formula is the standard method for turning those measurements into a hole length that fits the button's shape and still works with the garment. The other options aren’t about how large a buttonhole should be: pocket size, zipper length, and needle gauge relate to other features or sewing decisions, not to determining the buttonhole size. So using the buttonhole formula to compute the opening length is the correct approach.