Sunday, July 15, 2012

10 Tips on Sewing a Swimsuit

After several fruitless trips to the mall and other various stores searching for the perfect swimsuit, I once again decided to sew it myself.  Swimsuits are a great sewing project, because they take only a little bit of fabric, and you can actually make one that fits correctly and is the style you like.  But I know that lots of people are too intimidated to sew a swimsuit.  It really is not that hard, but you do have to be comfortable sewing with slippery, stretchy fabrics.  Here are my top 10 hints on how to sew a great suit:

1.  Start with a fresh, ballpoint needle!  I cannot stress enough how important it is to put a brand new needle in when you are sewing with swimsuit fabric.  It makes everything SO much easier.  I used size 11 ballpoint needles in both my serger and coverstitcher for this project.

2.  Use good quality swimsuit fabric.  You can get this at fabric stores like JoAnn's in the swimwear and dancewear section.  Look for it to be labelled as swimsuit fabric.  You should expect a high lycra (spandex) content -- maybe 20%.  You can also buy it at specialty shops online such as SpandexWorld.

3.  Pick a good swimsuit pattern.  You won't get a good product if you don't start with a good pattern.  KwikSew has several swimsuit patterns.  I haven't personally used any of them.  Jalie also has great swimsuit patterns.  The nice part about Jalie patterns is that they come in 22 sizes -- all the way from kids through adult -- in one envelope, for one price. The one I personally have used for myself is now out of print, but they have several at this page:  I would definitely check patternreview for specific reviews before purchasing a swimwear pattern.

4.  Or, don't use a swimsuit pattern at all!  You can choose patterns that aren't even meant as swimwear, but that give you the look and fit you want.  For my daughter, I wanted a swim shirt and shorts or leggings with an attached skirt.  I already owned patterns that would work just fine for this.  The swim shirt is just a raglan t-shirt.  I particularly like this raglan pattern because it comes up fairly high around the neck and has armbands also.  Because swimsuits need to be close fitting, I used a pattern two sizes smaller than what she would normally wear, and I just added extra length.  For the leggings and skirt, I downsized by one size (since the pattern for the leggings was already close fitting).  Both of these patterns are from Ottobre magazine, issues 3/2010 and 3/2011. 

5.  Use a 4-thread serger stitch.  If you are using a serger to construct your suit, use a 4-thread stitch.  Yes, a 3-thread stitch will give you more stretch, which would seem like a good thing, but you do not want the seams on your swimsuit to fail!  (Ask me how I know...)  If you are not using a serger, use a zigzag and a straight stitch combination, as explained in this Jalie tutorial.

6.  Don't cheap out on the thread.  Use Gutterman or Maxilock.  It really does make a difference.  These are seams that you do not want to break when you are out on a waterslide somewhere.

7.  Stretch your elastic correctly.  When making a women's or girl's traditional suit, you need elastic enclosed in the seams at these places: the leg openings, the arm openings, and the neckline.  For the arm openings and neckline, the elastic only needs to be stretched slightly to moderately when sewing.  Now this is the surprising part.  For the leg openings, the stretch of the elastic is not the same at the front as at the back.  For the front of the leg openings, you want to only slightly stretch the elastic, but at the back of the leg openings you want to give a moderate to strong stretch of the elastic.

8. Topstitch your seams.  I know it is tempting to skip topstitching.  But on a swimsuit or swimshirt, it is essential.  Because they fit closely on the body, and because they are constantly being stretched and pulled when worn, the seams will flip if not topstitched.  Let me show you what I mean.  Here is a close-up of the arm of my daughter's swimsuit:
If I did not topstich the seam allowance on the arm band, the floral print arm band would flip up when she was swimming.

9.  Line the front of the suit.  For an adult suit or a child's suit made in a light color, you really need to line the front of the suit.  You can buy tan swimsuit lining fabric at JoAnn Fabrics.

10.  Don't forget the boys!  It's easy to sew suits for boys, too!  A great source of fabric is Chez Ami.  They sell microfiber swim fabrics that are perfect for swim trunks.  Jalie has a board shorts pattern, or you can use any elastic waist shorts pattern.  Usually, swim trunks have a mesh inner short, so you will have to add that yourself if you are adapting a normal shorts pattern.

If you sew any swimwear, I hope you will comment with a link to pictures or at least a mention of your favorite pattern or fabric source!


  1. Love the suit! Looks like someone is very happy with it as well. :)

    1. Thanks, Becky! She is happy. She was doing a "swimming pose" in that picture.

  2. I have been trying to make some adjustments to my bathing suits. However, I keep running into problems where, the bottom thread isn't interlocking with the top thread. I have already re-threaded the machine and the bobbin properly. I understand I should use a Ball Point needle but, I am confused as to what type of thread I should be using and, if the thread on the bobbin should be a Wooly Tread.

    1. I often have that problem, but I notice that even though a BP needle is suggested, for some fabrics, a universal works better, especially if it is a very tightly knit fabric (dense). I use tex 27 thread on my machine and my serger- Maxi-Lock is fairly cheap ($2) at

    2. I do not use wooly nylon for swimsuits, but you could. I love Maxilock.
      A bent needle can cause threads to not interlock, or maybe a problem with tension?

  3. Thanks for the tips! Is there a specific brand/type of serger I should look for? Or any that I should avoid?

    1. I have a Juki Pearl, which I love. But for a low-end serger, many people love the Brother 1034D.


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