Seam classification is how seams are grouped based on characteristics they share, like their use, how they are made, stitch or machine type, cost, and where they are used.

Seams are grouped in more than one way. The two most common systems are by purpose or function: construction, finish, and detail seams (ASCS) and by how the fabrics are placed on the last step of the sewing machine (ISO). Seams can also be sorted by factors such as stitch and machine type, cost, and use.

The two main classifications are by their purpose or main function (ASCS system) and by how they are placed on the last step of the sewing machine (ISO system). Grouping by purpose divides seams into Construction, Finish, and Detail. Grouping by how they are made divides them into Superimposed (SS), Lapped (LS), Bound (BS), Flat (FS), and Edge-Finish (EF).

Classifying by purpose looks at the main job the seam does in the clothing, like joining pieces or finishing an edge. Classifying by how it is made looks at how the fabric layers are placed and sewn together. Both ways describe the same seam but from different points of view.

A class is the broad group based on how the layers are arranged, for example, construction or finish. A type is a specific seam within that group, for example, a felled seam (C100) or a welt seam (C110). One class includes many types.

A stitch is the individual loop of thread made by the needle, the basic unit of sewing. A seam is the line where fabric pieces (or folds) are joined by a row of those stitches. Put simply, stitches build a seam, and a seam gives the garment its structure, finish and function.

No. Seam classification is about how fabric pieces are joined, while stitch classification is about how the thread loops are made. A single seam can be sewn with different stitch types, so the two classifications work together but describe different things.

Understanding seam types clearly helps designers and product developers describe seams correctly on a tech pack, which reduces miscommunication with factories, speeds up production, and lowers mistakes.

At ABC Seams, we classify seams by their purpose or job, dividing them into Construction, Finish, and Decorative seams. This way is easier for designers and developers in daily work, without needing to know every step on the sewing machine, so they just focus on the garment’s final look.

First, read the garment and its needs: fabric weight and behaviour, the seam’s function and stress, its location on the body, the quality level, and your time, cost, and machines. Then choose the seam in three steps:

a) Purpose (seam category): is it a construction, finish, or detail seam?
b) Structure (seam type): how the layers sit, for example, single fold hem (H100) or double fold hem (H110).
c) Stitch and topstitch: the stitch and topstitching type that suit the fabric and the job. For example, chain stitch (stitch type) and edge stitch (topstitch type).