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To Set Undies Flat or In the Round?

undies (1 of 1)

The same burning question that haunts sewers when attaching a sleeve to an armhole also bedogs makers of intimates. To set elastic flat or in the round? One way is easier than the other, but the other way is considered the correct method. Most of the big pattern companies inexplicably have sewers set sleeves in the round, so that’s the method they learn first. But once he or she tries the flat method, they usually never go back. Of course, the project at hand has some say in the matterΒ (i.e. setting a sleeve in a t-shirt versus a tailored jacket). Same goes for attaching elastic. Newbies are first taught to set elastic in the round, but never go back after trying the flat method. For me, the correct method is the one that yieldsΒ the higher quality finished product, which in the case of undies is setting the elastic flat on the leg opening and setting the elastic in the round at the waist. Here’s why. The leg opening is curved, so it is a lot easier to set it flat. However, the waist opening is straight (not curved), so it’s not a hassle setting the the round. The only difference to consider when choosing between the two is how the elastic will be finished. When setting in the round, you will most likely overlap the elastic 1/2″, which is flatter than when elastic is set in the round. In that case, the elastic will have to be finished separately and tacked either forwards or backwards.

What about you? What method do you use and why?


  1. Reply

    Carlee McTavish

    I have yet to make my own undies, but in terms of sleeve setting, I certainly prefer setting them in flat. It takes me about 1/2 the time to set it in the round (and way less swearing too).

    • Reply


      I prefer to sew both waist and leg openings in the round because it does not make thickness against the skin, except when undies are made with lace and one other fabric as central panel, I sew them leg openings only in flat. Bonne soirΓ©e from France

  2. Reply

    Alessa Farbenfreude

    Hah, only a few days ago I was wondering why I had never tried attaching my undie elastic in the flat! I shall certainly try that now! I think I’ll keep attaching the waist elastic in the round, though, since I prefer to have only one seam in the back…

    • Reply

      Maddie Flanigan

      Isn’t it amazing how great something so small can be to our sewing lives. It’s like, “how did I ever do it before?” πŸ™‚

  3. Reply

    Mary Behrens

    I prefer to do both in the round only because I can adjust where the elastic overlaps so I don’t have a lump pressing on my hip or thigh when wearing jeans or other snug clothing.

  4. Reply

    Rose in SV

    I apply the FOE to the leg openings when the panty is flat (after the front and back have been attached to the crotch and the lining). then I sew up the side seams, then apply the waistband (in the round.). My upper outer thighs more forgiving for overlapping elastic than my inner thighs.

  5. Reply


    I love all the thought you gave to this, and your conclusions make so much sense. And those panties look like they will be a beautiful match to your bra. Lovely.

    • Reply

      Maddie Flanigan

      Those were the undies that matched my bra!

  6. Reply

    Natasha Estrada

    Anything that can be sewn flat should be sewn flat. Only in a few cases is sewing in the round desirable. Tailored sleeves are one because you might want to tip them forward or back. But in general flat. Sew your pockets on before everything else too.

  7. Reply

    Lady ID

    I set my sleeves in the round because that’s the way I’ve always done it plus I feel like I have more control over the amount of “bulk” at the underarm seam.

  8. Reply


    In the round is considered higher quality . Flat sewing is taught for factory methods and to speed up construction,I believe.. I don’t like the little serged bump that flat sewing makes since the hem is interrupted. It looks cheap,but I’m picky.

  9. Reply

    Brenda Price

    Hi, I was wondering if anyone knows how or what is used to make the rubber type leg edging that keeps panties from showing while in stretch pants, it is awesome and I’d really appreciate it if someone could help with this. Thank you very much!

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