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Stitch Classifications

Here's something you might be asked by your pattern maker, factory, or consultant... "What stitches do you want used in your design?"
By Amy Ashworth
On March 8, 2021

Hello Creatives!

Here's something you might be asked by your pattern maker, factory, or consultant... "What stitches do you want used in your design?"

This is an important question because it effects many aspects of your design, from strength, durability, and usefulness to look and cost. If you don't have a clue about stitches, you're in the right place. And even if you do, read through to the end for some great links to some excellent tools that will help you develop your tech packs even more efficiently!

Due to the comprehensive work of ISO (International Organization for Standardization), the world's largest developer of voluntary International Standards, we can use a classification of stitches that is universally understood and communicated-- using the ISO 4915 Stitch Matrix. WAIT! Don't gets better, honest. Founded in 1947, ISO has published 23,613 International Standards covering almost all aspects of technology and business, and the standard referenced above can be really handy for you in making your tech packs. In fact, it's essential. If you got bored just now, and noticed that the acronym ISO is switched a little...(why isn't it IOS? After all, they were around waaay before Apple!), your observation is correct. The truth is, What? No, wait... seriously, don't leave, I will get to talking about what the stitches are, I really will. The International Organization for Standardization is headquartered in Geneva, Switzerland, and exists by a different name in every language. Rather than having several acronyms in different languages, they chose ISO as its abbreviated name. The word ISO is derived from a Greek word isos meaning equal. Aaaand, back to the topic.

So let's say you are designing an article of clothing, and you have it all sketched out, you know how it should look, and even the fabric you want. Different fabrics call for different types of stitches based on what you expect from it in terms of stretching, stability, and the type of fabric you're using. It is normal for a single garment to be comprised of many stitch types.

Stitches are broken into six main classes :

  • Class 100 Single Thread chain stitches
  • Class 200 Hand stitches
  • Class 300 Lock Stitches, hook & bobbin
  • Class 400 Multi-thread chain stitches
  • Class 500 Overedge and safety stitches
  • Class 600 Cover Stitches

Let's take a quick look at the most common stitches within these classes, that you will likely need to know (and choose from) as you develop your product.

103 is a chain stitch that is commonly used in a blind hem. There are no visible stitches on the face side, and a chain pattern is visible on the underside. It's formed by a thread carried by a single, curved needle. AC Ashworth & Company uses the blind hemmer on our fine dresses and menswear. When designating this stitch, your production team will need to know SPI (stitches per inch) and whether or not you want a skipped stitch in between.

103: Chain stitch

301 is the most common of all construction stitches. It's a straight stitch formed by a single needle and bobbin; used for seaming and top stitching. It is a strong stitch that will not stretch. You'll be asked for the SPI.

301 : Lockstitch (straight stitch)

304 is a lockstitch, but in a zig-zag formation. It is used on areas that must be strong, but also stretch; such as intimate apparel and athletic wear. A special lock stitch machine is also used to create rectangular button holes. You will need to specify the width ("throw"), and the length (density), which is measured in SPI. The top and underside look similar, but are not identical.

304: Zig zag stitch

401 is a single chainstitch. This stitch is used in combination with an overedge (see 516) to form a safety stitch in wovens, to seam and overedge in one step. Because of its excellent elasticity, it is often used in fabrics that must stretch. Used alone, it is a perfect choice for a knit or spandex seam, when the raw edges must be pressed open ( and therefore should not be serged together) such as V necks and backs. It is not quite as secure as a lockstitch, and is somewhat bulky in comparison. When choosing this stitch, specify SPI.

401: Chain stitch

406 & 407 are double and triple needle bottom cover stitches. These stitches are great for hemming and coverstitching knits, and making belt loops. Most home (portable) cover stitch machines have these features. You will need to specify the needle spacing and SPI.


408 is a coverstitch with double chain stitches on the underside, comparatively the opposite of seam 406. You've probably seen this stitch connecting your pocket to the facing in jeans or chino pants. This 5-thread stitch also makes durable, flexible decorative seams in sportswear. The machines that make this stitch have a fixed width and SPI; if you are using this stitch to seam sportswear, your pattern must be cut accordingly.

408: 2 needle chainstitch with cover thread

503 is a simple overedge stitch, using 2 threads--one needle, and one looper. Most commonly referred to as "serging" this stitch is unsuitable for any seam or stress-bearing function. It is a good choice for finishing raw edges in unlined garments. Specify the width bite and SPI.

503: 2-thread overedge

504 is a three-thread overedge stitch. More durable than 503, it is used to finish heavier and more fray-prone fabrics such as linen and wool. It can be used in seaming lightweight knits if little seam stress is expected. This stitch will add a bit more bulk, so is not the first choice for sheers and lightweight edge finishing. As with 504, specify width bite and SPI.

504 3-thread overedge

505 is a variation of 504, creating an interesting change in utility. The difference lies in the tension: the lower looper thread is tighter, and the needle thread is looser in this stitch, creating a double purl on the edge. Unike 504, this stitch should be used for serging only, in fabrics that fray excessively, and require the extra layer of abrasion protection on the edge. Specify width bite and SPI.

505 3-thread overedge

512 & 514 are both 2-needle, 4 thread configurations. Stitch 512 presents as a mock safety stitch, providing a flexible seam and overedge finish for medium weight knits and light to medium wovens. Stitch 514 has an extended loop, which places the needle threads inside the stitching. Specify SPI.


516 is a 5-thread safety stitch perfect for seaming and finishing midweight to heavy knits and wovens. It is formed by combining a chain stitch and an overedge stitch. Plan seam allowances for the width of this stitch; and be sure the design does not require the seams to be pressed open. This stitch will make impressions on thinner fabrics and is more expensive to process due to thread consumption. When properly applied, 516 remains as an industry standard for strong, flexible seams and durability. Specify needle spacing bite, and SPI.

516 : 5 Thread Safety Stitch

Moving on to the 600 class, we have the 2, 3, and 4 needle cover stitches. These stitches add a decorative touch to binding, lap seams, and coverseams in sportswear, underwear and fleece. Specify needle spacing for 602 & 605, and SPI for all.

602: 2-thread coverstitch
605: 3-needle coverstitch
607: 4-needle coverstitch

I hope this has been helpful in planning your designs! As always, if you have questions or need help in planning your line, contact us today!

Lastly, here's a place to download a quick-reference list of all the common stitch class types.

I found it helpful to print the matrix, laminate, and hang on a hook near my work area.

Another great reference tool I use often is a book called "101 Seams" by ABC Seams. While the numerical designations are different from ISO, the book does an excellent job of explaining many types of seams and what their best uses are. You can purchase or download a copy here

And lastly, as you prepare your costing sheets and plan for how much thread you need for your production run, these thread consumption calculating spreasheets ("anacalc") will save you time and frustration! Just plug in the information from your pattern specification sheet and it does all the hard work for you!

All the best!


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