14 Tips: How to Sew a Swimming Suit

heather handmade sewing

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Use these tips to learn how to sew a swimming suit. Once you know the way to sew swim stretch fabric you can make any suit.

I remember taking a swimming suit sewing class in college, and I was completely amazed at how easy it was to sew a swimming suit and how little fabric it required. It was one of my very favorite classes, and after that class I wanted to sew ALL the swimming suits.

I have sewn plenty of swimming suits, and I love making one every time I get the chance. Since I took the class AND have sewn lots of swimming suits, I’ve learned lots of tips for successful swimming suit sewing that want to teach you today!

There is a video showing ten tips to sew a swimming suit and how the fabrics stretch at the end of the post.

how to sew a swimming suit
How to Applique on Stretch Fabric // heatherhandmade.com

Do you want some ideas for sewing projects? Check out one of these lists:

how to sew a swimming suit

Tips to Sew a Swimming Suit

1. Use a stretch needle* and stretch twin needle*.

This is very important since it will work the best with fabrics with lots of stretch. These needles have a rounded point so they don’t break the fibers, and they have a deeper shank in the back for more space to catch the thread.

14 Tips to Sew a Swimsuit // heatherhandmade.com

2. Cut with a cutting mat, rotary cutter*, and pattern weights.

Swimming suit fabric and lining is stretchy and slippery and really hard to cut. This is the easiest way to get the most accurate cut.

14 Tips to Sew a Swimsuit // heatherhandmade.com

3. Use clear elastic* or treated elastic.

Chlorine and salt water is really hard on elastic and over time it’ll remove the elasticity. I prefer clear elastic because it’s thin and change even when sewn on.

14 Tips to Sew a Swimsuit // heatherhandmade.com

4. Learn about the different swimming suit fabrics and linings.

There are multiple kinds of fabric and linings so you need to learn about each other them.

  • Polyester Spandex* – more expensive, less stretch, better returnability, longer-lasting, less available
  • Nylon Spandex* – less expensive, most stretch, loses shape over time, easily snags and runs, easy to find, and most common.
  • Swimming suit Lining* – The cheapest and most available swimming suit lining.
  • Power Knit* – Not recommended to use everywhere, but it works well for a little bit of shaping.
14 Tips to Sew a Swimsuit // heatherhandmade.com

5. When sewing elastic into a circle, overlap the ends and pin parallel to the edge.

This is the easiest way to keep the ends together while sewing. It’s tricky to sew something so slow. I use a zigzag stitch multiple times to sew my ends together.

14 Tips to Sew a Swimsuit // heatherhandmade.com
14 Tips to Sew a Swimsuit // heatherhandmade.com

6. Use a lining.

I don’t know about you, but I prefer complete coverage and no sneak peaks. The best way to insure this is to use a lining. It also helps your swimming suit last longer.

7. Make a muslin out of your swimming suit lining.

You want to have a swimming suit that fits perfectly, but you’ll need to make a muslin to test the fit. When you make a muslin out of swimming suit lining it’s much cheaper than your swimming suit fabric.

14 Tips to Sew a Swimsuit // heatherhandmade.com

8. Learn about different stretch stitches and when to use them.

Test which stretch stitch you like the best. I prefer a tight zigzag for seams, a serged edge to finish all the edges, and a 3-step zigzag to attach elastic.

14 Tips to Sew a Swimsuit // heatherhandmade.com

9. Your swimming suit should have negative ease.

There isn’t a formula for this (at least I’ve never found one), but you want a fitted swimming suit since it will stretch out a little in the water.

10. Practice practice practice

make samples to practice sewing with fabric. Make a sample with stretch stitches and your swimming suit fabric with the lining. Make a sample by pinning the elastic to the edge.

14 Tips to Sew a Swimsuit // heatherhandmade.com

Make a sample with your swimming suit fabric and lining and attach some elastic. I like to use a 3-step zigzag to “baste” it on and then I serge the edge of the fabric and elastic.

14 Tips to Sew a Swimsuit // heatherhandmade.com

Make a sample with your elastic attached to your swimming suit fabric. Fold the elastic over and secure with a twin needle.

14 Tips to Sew a Swimsuit // heatherhandmade.com
14 Tips to Sew a Swimsuit // heatherhandmade.com

11. All straps should have elastic hidden inside to give it strength and returability.

Trust me, I tried making straps without elastic and it didn’t keep up my swimming suit!

12. Add swim foam cups* as late as possible so you can try it and get the right placement.

I like to add my cups right before I close the edges with elastic. This is the latest possible time to add them.

14 Tips to Sew a Swimsuit // heatherhandmade.com

13. Once the swim foam cups* are attached to the lining, cut out the swimming suit lining in the area of the cups to prevent flattening.

Can you see the raw edges of the lining on the edge of the cups? I cut out the lining that was within the edges of the cups. If you leave lining in it’ll flatten you chest and make the cups obsolete.

14 Tips to Sew a Swimsuit // heatherhandmade.com

14. If hemming the edge, use Soft Stretch* for a perfect hem.

I only use it on swim shorts, a tankini hem, or a swim skirt. I don’t use it on the edges where I attach elastic. Soft Stretch prevents tunneling and creates a crisp hem.

A great place to start out sewing swimming suits is with the Kwik Sew’s Swim and Actionwear* because it comes with all the basic patterns you need. Once you learn what alterations you need to make and the basics of sewing swimming suit fabric, you can alter the pattern as much as you want to get your dream swimming suit!

how to sew a swimming suit

If you make something using this sewing project, I’d love to see! Please share it on social media with the hashtag #heatherhandmade and tag me!

heather sewing

I believe small sewing moments can create great joy. Find your own “right” way to sew. -Heather

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What kind of thread do you use? I have tried using various synthetic threads but must not be using the right thing because they all end up bleaching out after a few swims in the pool.

What type of product are you referring to when you say you use Soft Stretch? Is it an interfacing?Do you have a link to it?

Thank you! I’m going to try replacing the front lining of a favorite swim suit. I think this is an act of bravery or foolishness. I’ll know when I see the results of my effort.

Thank you for your great tips. I’ve been wanting to make the leap into swimwear, and I now know a lot more about the process thanks to you! The pictures were very helpful and your page will be open when I make a swimsuit.