How to Sew a Reversible One-Piece Swimsuit in 6 Simple Steps

Edgewater Avenue
by Edgewater Avenue
7 Materials
5 Hours

Hey, everyone! Today I’m going to show you how to sew a reversible one-piece swimsuit. The pattern I’ll be using is a basic, simple one-piece with a low cut in the front and a deep cut in the back.

This stunning DIY one-piece bathing suit will give you moderate to full coverage. Also, if you’re a beginner, then sewing a one-piece swimsuit is perfect to start on.

Tools and materials:

  • Poppy One-Piece pattern
  • Scissors/rotary cutter
  • Sewing machine
  • Swimwear fabric
  • Swimwear elastic
  • Lining fabric - nude nylon spandex
  • Pins
Cutting out the one-piece swimsuit pattern

1. Cut the pattern

Let’s start cutting out the pattern. Use some weights to hold the pattern in place as you cut. Also, use a ¼-inch seam allowance when cutting. You should now have one front piece and one back piece. 

Cutting out the lining for the swimsuit

Now, do the same with the lining pieces, cutting one for the front and back. Use your main pieces as a guideline as they already have the ¼-inch seam allowance. 

Pinning the lining fabric to the main fabric

2. Match and pin

Next, match the front and back main pieces, right sides together. 

DIY one-piece bathing suit

Pin the leg holes, armholes, and neckline on the front and back pieces, respectively. The only openings should be the sides, gusset, and straps. 

How to sew a one-piece swimsuit

3. Sew the pinned areas

Go ahead and sew all of the pinned areas. 

Elastic for the one-piece bathing suit

Sewing elastic along the swimsuit seams

4. Attach elastic

Once those seams are all sewn, go back and attach elastic onto all the stitched seams. 

How to make a one-piece swimsuit

5. Assemble the swimsuit

Ok, it’s time to assemble the DIY one-piece bathing suit! This can be tricky, so be sure to follow the next steps closely. Take the front piece and turn it right sides out. 

Inserting the front piece into the back piece

Insert the front piece inside the back piece through the open side seam. Make sure each seam of both pieces aligns correctly and that the fabric is right sides together. 

Aligning the traps of the DIY swimsuit

Also, make sure the straps align, so ruffle the fabric if you have to get everything smooth as possible. 

Pinning the gusset and the straps

Pin the gusset and straps. 

Sewing a one-piece swimsuit

Next, sew straight across the strap openings and gusset. You’ll be sewing four layers into place, so do this carefully. 

Pinning the sides of the swimsuit

Pinning the swimsuit ready to sew

Now, it’s time to sew the sides. So, align each sides’ side pieces and pin, as shown. The sides are a little more complex as it does require you to stretch the fabric and fiddle around with the layers until they properly align. 

How to sew a reversible one-piece swimsuit

Sew down the sides and make sure all four layers are catching. 

Tip: Take your time with this step; it can be tricky. 

Seam ripping a small hole in the swimsuit

6. Turn right sides out

Now, seam-rip a small area on the back piece so that you can pull the swimsuit right sides out. You can actually leave a gap when sewing the swimsuit, but sometimes I forget to do this.

Turning the fabric right sides out

Now, take the suit back to the right side through the hole. 

Sewing up the gap with an invisible stitch

Stitch the gap with an invisible stitch. 

DIY reversible one-piece swimsuit

Back of the DIY one-piece swimsuit

How to sew a reversible one-piece swimsuit

Here’s the final product! This one-piece is nice and snug, and it does have a pretty low cut in the front, which is flattering for a smaller bust. If you have a larger bust, you can increase the neckline by an inch or two. Otherwise, this swimsuit has a very nice contour as is.

The best thing about this swimsuit is that you can turn it inside out and you have a completely different design! I hope you learned how to sew a reversible one-piece swimsuit now! Thanks for joining me.

Suggested materials:
  • Poppy One-Piece pattern
  • Scissors/rotary cutter
  • Sewing machine
See all materials

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