Know Your Terminology: Overlock Stitch vs. Flat-Felled Seam

While it’s obvious that stitching is what holds your pair of selvedge jeans together, what’s not so obvious are the differences between all of these stitches. There’s a chain stitch, lock stitch, topstitch, whipstitch, overlock stitch, flat-felled seam…let’s just stop there. For this article, we’re going to focus on the qualities and differences of those last two: the overlocked vs. flat-felled seam.

Overlock stitch vs. Flat-felled seam -

Overlock stitch (image c/o Strawbazies)

First, let’s talk about overlock stitches. An overlock is a stitch that sews over the edge of one or two pieces of fabric for edging, hemming, or seaming. It has a recognizable appearance, and is often known as “serging.” Classified by the number of threads in each type, an overlock features threads that often loop under and over each other.

Overlock stitching is strong enough, but its winning factor is how efficient it is. There are industrial sewing machines that are designed to solely produce overlock stitches, and they run at very high speeds–anywhere from 1000 to 9000 rpm.

However, it’s important to not confuse efficiency with quality–as many selvedge denim fans can appreciate. Overlock stitches that come into frequent contact with the wearer (like say, a crotch prone to blowouts) end up not being as durable as one may think. Instead of stopping fraying from the outset, it merely slows it down due to the interwoven nature of its threads. Luckily, flat-felled seams exist.

Overlock stitch vs. Flat-felled seam -

At a base level, a flat-felled seam is an overlapping seam that’s sewn flat. Placing one edge inside a folded edge of fabric, the fold is then stitched down to create a flat surface. Extremely durable and sturdy, less threads are exposed to the wearer, leading to less fraying. Aside from that, flat-felled seams tend to look much cleaner and more appealing.

Overlock stitch vs. Flat-felled seam -

Overlock stitching (far left and far right) compared with flat-felled seams (middle)

Of course, any particular brand has its own views on their stitching methods and the hours that go into them, so please take this simple guide with a grain of salt. Denim durability is a constant point of conversation, enough so that people now generally understand that they should wash their jeans if they want stitching to last. Either way, feel free to shop more confidently now that you have a few more stitching terms in your arsenal.

Austin Bryant

Austin is a denim enthusiast that hails from Boston, Massachusetts. He works in the fashion industry and has a passion for all things visual. His photo blog is Men of Charisma and his adventures can be seen through his Instagram: @ausbry

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  • Chris wcrd

    Good clear concise article. Thanks :)

  • Altoclefchris

    It is all about double felled inseams

  • dnugget

    If you plan to get your pair of raws altered (hemmed or tapered, for instance), is it easier/cheaper for jeans with overlock stitching rather than flat-felled seams?

    • Young

      it doesn’t make a difference with a hem. with tapering a jean, with overlock stitching, you can taper the jean from the inside if you don’t wish to alter how the selvedge out seam looks but with felled seams, it’s not possible so you can only taper from the outseam and change how the selvedge looks. tapering the jean from the inseam side might actually cost a little more.

  • Hing

    what’s the one in the middle?

  • sean

    i’ve been wondering about this, so thanks for the article!

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  • D4niel

    Uh, how about a larger image showing the seams?


    Ive had many discussions about Overlock vs Felled seams over the past 13 years –

    When i was studying Fashion Design, I was taught to “always avoid an over locker” The over locker was designed to speed up production – leading to a cheaper garment – maybe its just a British thing.

    Most Denim Designers seem to think its normal to have it, some even pride them selfs on showing it off as a feature.

    Ask any collector of Vintage and tailoring garments from 100 years back – nearly everything was felled. Even some of the garments Mike Harris finds down Silver Mines are felled seams on Centre Back, and Yoke Seams-

    Ive heard many discussions about – “Felled seams are too bulkily, we prefer over lock”- ( which i disagree on) This is mainly from lazy tailors who don’t want to taper the jean – ( as its little extra work) or are scared there gonna break a needle on there Union special 43200G when they hem it after –

    Altoclefchris – completely agree ! – if its not selvage garment ( with a felled seam in inseam) then it should be doubled felled as standard.

    Something is Artcle did not touch on, is the more labour intensive and Ultra amazing Single Needle Felled Seam. Our Friends from Rising Sun, and Warehouse Japan do it alot – even 3×1 do it – Below is a quick mock up which explains, plus an image of doubled felled leg seam – which is imo the best way to finish a non selvage pant.


    naked and famous is the worse for using serger instead of flat felled and overlock seams