Stitch and seam types: ISO 4915 and ISO 4916
Two standards, read together. ISO 4915 says how the thread interlocks; ISO 4916 says how the fabric plies meet. Every tech pack line depends on both.
What is the difference between ISO 4915 and ISO 4916?
ISO 4915 classifies the stitch, meaning how the threads interlock, into six classes from 100 to 600. ISO 4916 classifies the seam, meaning how the fabric plies are arranged, into eight classes. A complete specification needs both, written as the seam designation followed by the stitch type.
What is a 301 stitch used for?
Stitch type 301 is a two-thread lockstitch and the default for woven garments. It forms side seams, sleeve inseams and topstitching. It is secure and will not unravel from either end, but has limited stretch, so knitwear and denim inseams normally use a 401 chainstitch instead.
ISO 4915 stitch classes
ISO 4915 groups every sewing stitch into six classes by how the threads interlock. The class is the first digit; the full type number identifies the variant.
| Class | Name | Threads | Typical use |
|---|---|---|---|
| 100 | Single-thread chain stitch | 1 | Unravels easily; basting and temporary work |
| 200 | Originating as hand stitches | 1 | Hand-stitch simulations, saddle stitching |
| 300 | Lockstitch | 2 | 301 is the default for woven garments — side seams, sleeve inseams, topstitching |
| 400 | Multi-thread chain stitch | 2+ | 401 attaches sleeves to armholes; lap-felled seams in denim |
| 500 | Over-edge chain stitch | 1–4 | 504 overlock neatens a raw edge as it seams |
| 600 | Covering chain stitch | 3–9 | Flatlock and coverstitch on knitwear hems and necklines |
ISO 4916 seam classes
ISO 4916 classifies the seam itself — how the plies are arranged. It is read alongside ISO 4915: the stitch says how the thread locks, the seam says how the fabric meets.
| Class | Name | What it is | Stitches used | Application |
|---|---|---|---|---|
| 1 | Superimposed | Two or more plies laid over each other and joined near an edge. | 301, 401, class 500, 516 | Load-bearing seams in shirts and lingerie |
| 2 | Lapped | Plies overlaid, plain or folded, joined with one or more rows of stitching. | 401 chainstitch | Lap-felled seams in jeans; French seams in rainwear |
| 3 | Bound | A binding strip folded over the edge and stitched on both sides. | 401 or 301 | T-shirt necklines, elastic braid on briefs |
| 4 | Flat (butt) | Two edges butted together, not overlapped, then oversewn. | Zigzag lockstitch, chainstitch, class 600 | Fine knitwear and underwear where bulk cannot be tolerated |
| 5 | Decorative / ornamental | Stitching along a line or design on a single ply. | Varies | Pin tucks, applied braid |
| 6 | Edge finishing / neatening | A single raw edge folded or covered to stop fraying. | Class 500 over-edge | Serging trouser panels, flys, facings |
| 7 | Attaching separate items | Adding a separate component to an edge, e.g. elastic braid. | Varies | Elastic onto briefs |
| 8 | Single-ply construction | One piece turned in on both edges, usually with a folder. | Varies | Belt loops, belts |
How a seam is written down
A stitched seam carries a five-digit designation. The first digit is the seam class (1–8). The second and third are counting numbers (00–99) that distinguish where the needle penetrates. The stitch type is then written after the seam designation, and where two or more stitches are used they are listed left to right.
So a tech pack line reading 1.01.01 – 301 means a superimposed seam, first variant, sewn with a lockstitch.
Why this matters on a production floor
The stitch and seam numbers are what a buyer’s tech pack specifies and what a QC audit checks against. Getting them wrong is a rework cost, not a paperwork error: a 301 lockstitch where a 401 chainstitch was specified will fail a stretch test on a denim inseam.
Scan ERP records the operation against each bundle as it is scanned, so the operation actually performed is traceable back to the lot — see shop floor control for how that record is built.
Copy this attribution
Scan ERP — Stitch & Seam Types — ISO 4915 and ISO 4916. https://scanerp.pro/stitch-types/
Compiled from ISO 4915:1991 stitch types and ISO 4916:1991 seam types, as summarised in the Coats Sewing Solutions technical bulletin. This page is a working summary, not a substitute for the standard itself — buy the ISO text where a contract requires it. Last reviewed 29 September 2026.