How To Sew A Flatlock Stitch On Your Serger

If you have store bought athletic apparel, you may notice the beautiful flatlock stitching that keeps the garment together. Now achieving a real flatlock stitch requires a fancy-pancy flatlock machine that comes with a price tag in the thousands. But fear not! You can achieve a lovely faux flatlock stitch with your serger. So let’s get to it.


Before anything else, turn off your serger, set all of your tensions to zero and remove your thread. Then remove your right needle, disengage your knife and engage your stitch finger.



After making all of these adjustments, you’re going to go ahead and thread your machine as usual. The thread you use in your upper looper is what’s going to be the main thread across the front of the stitch.

Set your tension settings to the following:

Left Needle  0
Upper Looper  4-7 (depending on your machine – mine is set to 5)
Lower Looper  4-7 (depending on your machine – mine is set to 5)


Finally, shorten your stitch length to around 1 and your differential feed around 1 as well.



The main difference in how you’re going to sew is that you’re going to be sewing with the wrong sides facing each other.


Sew your seams as usual and after you sew them you’re just going to pull the fabric pieces away from each other to flatten the stitch. This is what your flatlock stitch should look like when you’re finished:



What To Sew

Athletic apparel is an obvious choice for flatlock stitches but it makes a fun decorative element to lot of different casual pieces. The faux flatlock stitch with your serger will be slightly more bulky than the flatlock you’ll achieve from an actual flatlock machine, but it gives a very professional finish and look without spending thousands of dollars.

Here are a pair of Inspire Athletic Tights I sewed up with faux flatlock seams. Soooooo comfy!

Editor’s Note: Enjoying this unique sewing tip? Put it to use on our Nicolette Colorblocked Tee!



Pregnant girls like athletic pants too!


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5 thoughts on “How To Sew A Flatlock Stitch On Your Serger”

    1. No ma’am! I haven’t had to reinforce them in my own experience 🙂 It is important to use fabric with the proper stretch though. Not enough stretch can definitely put too much stress on the seams.

  1. hi ,
    I was wondering if you removeD any of the seam allowance. If so how much? I just sewEd up a paIr of inspire and took out 1/8 seam allowed but they were still To big.
    Sorry for the caps i couldn’t get It to turn off.
    Thank you ,

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