What Is a Buttonhole? Types and Sewing Techniques

The size of a buttonhole is determined by the button it must accommodate. The standard formula is button diameter plus button thickness plus one-sixteenth of an inch for ease. A flat, two-hole shirt button requires less ease than a domed or thick shank button. If the buttonhole is too small, the button will be difficult to fasten and will strain the fabric. If it is too large, the button will slip out, and the garment will not stay closed.

Placement is equally critical. On a center-front closure, buttonholes are typically sewn horizontally, which allows the button to settle naturally at the outer end of the buttonhole when the garment is under tension from body movement. Vertical buttonholes are used on plackets, bands, and areas where the alignment must remain precise, such as the center front of a tailored shirt. The spacing between buttonholes affects the garment's drape and the amount of gaping between closures. The tech pack should specify the exact buttonhole positions measured from a reference point like the center front line and the neckline seam.

Machine buttonholes are the most common type in modern garment production. A buttonhole machine, or a sewing machine with a buttonhole foot, creates a reinforced slit with bar tacks at each end and closely spaced satin stitches (zigzag) along both sides. The result is a clean, uniform buttonhole produced in seconds. Industrial buttonhole machines are specialized for this single operation, capable of sewing thousands of identical buttonholes per shift with programmable length, stitch density, and bar tack configuration.

Keyhole buttonholes are a variation where a round opening, or eye, is cut at one end of the buttonhole. This design accommodates the shank of thicker buttons and is standard on tailored jackets, blazers, and coats. The keyhole prevents the button shank from distorting the straight portion of the opening. Machine-made keyhole buttonholes require a specialized industrial machine or a domestic machine with a keyhole buttonhole stitch program.

Hand-worked buttonholes are the hallmark of high-end tailoring and couture garments. They are created using a buttonhole stitch, also called a tailor's buttonhole stitch, which forms a knotted edge that is both strong and distinctive in appearance. The process involves cutting the slit first, then working a series of closely spaced stitches around the opening with silk or gimp thread. The knots form a raised bead along the edge that resists fraying and adds a textural quality visible to the discerning eye.

Creating a single hand-worked buttonhole takes several minutes, compared to seconds for a machine-made one. This time investment is reflected in the price of the garment and is a quality indicator that consumers of bespoke and luxury tailoring expect. Hand-worked buttonholes also allow for subtle customization, including contrasting thread colors, varying stitch densities, and asymmetric keyhole shapes that give each garment an artisanal character.

A bound buttonhole, sometimes called a piped or welted buttonhole, uses strips of fabric to create a finished opening that resembles a tiny double-welt pocket. The edges of the slit are enclosed in fabric lips rather than stitched with thread. Bound buttonholes are commonly found on structured garments such as coats, jackets, and evening wear, where they contribute to a refined, clean appearance. The technique requires precise cutting and stitching, and any misalignment of the fabric lips is immediately visible.

Constructing a bound buttonhole involves marking the opening, attaching two strips of fabric, cutting the slit between them, turning the strips to the inside, and pressing. The process is more labor-intensive than machine or hand-worked buttonholes but produces a luxurious result. In production, bound buttonholes are typically assigned to skilled operators and are a common source of quality rejects if tolerances are not closely maintained.

A well-written tech pack includes a buttonhole specification that covers length, type, placement coordinates, thread color, stitch density, and orientation. For keyhole buttonholes, the eye diameter and the direction of the eye relative to the garment edge should be noted. If the garment uses multiple button sizes, such as a smaller button at the collar and larger ones on the front placket, each buttonhole length must be specified separately.

The tech pack should also indicate the buttonhole sequence in the production flow. Buttonholes are typically sewn after the garment body is assembled and pressed but before the buttons are attached. This allows the operator to position the buttonhole machine accurately on the finished garment. Including a full-scale buttonhole placement diagram in the tech pack, rather than relying solely on written coordinates, reduces misinterpretation and ensures consistent results across production lots.