Straight and Keyhole Buttonholes
Two buttonhole shapes cover most garment production. The straight buttonhole is a parallel-sided slit with bar tacks at both ends, and it suits light to medium fabrics, shirts, blouses and many knit applications. The keyhole buttonhole widens into a rounded eye at one end; it is used where a button needs clearance, such as heavier coats, jackets and tailored garments. The shape chosen affects the machine configuration, the cutting method and the stitch density, so it should be fixed before comparing options.
Lockstitch and Chainstitch Formation
Buttonholes are formed either with a lockstitch or a chainstitch.
- Lockstitch buttonholes use a bobbin thread and are the more common choice for woven garments where a clean, secure finish is wanted.
- Chainstitch buttonholes use a single needle thread and are typically chosen for stretch fabrics and knitwear, where the stitch can extend with the material.
- Both formations can be paired with a cutting step before or after stitching, depending on the machine design.
- The formation also influences thread consumption, maintenance routine and the operator skill required.
Sizing by Button Diameter and Garment Type
Buttonhole length is generally set from the button diameter plus a small allowance for fabric thickness and stitch bulk. A practical starting point is to measure the button, add clearance for the fabric being sewn, then confirm the bar tack or eye position. Garment type guides the decision: shirts and light dresses take short straight holes, outerwear takes longer holes and often the keyhole shape, and knitwear may need a reinforced or gimp-corded finish. Because the correct setting depends on the actual button, fabric and seam, specifications are confirmed on quotation rather than published as fixed figures.
Buyer Checklist Before Requesting a Quotation
Prepare the following so the supplier can match a machine to your work:
- Buttonhole shape: straight, keyhole, or both.
- Stitch formation: lockstitch or chainstitch.
- Button diameter range and expected hole length.
- Fabric type, weight and stretch behaviour.
- Cutting method preference and whether a separate cutter is needed.
- Typical daily output and number of shifts.
- Power supply, working voltage and available floor space.
- Spare parts and service support expectations.
Buttonholes are usually only one part of a fastening line; if your production also sets the buttons, see Button Sewing and Attaching Machines for the matching category. For garment machinery and spare parts, ANYSEW offers a one-stop purchasing service covering product customisation, quality inspection, installation and debugging, after-sales maintenance, spare parts supply, and logistics and transportation. Certificates available upon request.
To discuss your buttonhole requirements, share the checklist above through our contact page and request a quotation.