August 14, 2014

Tutorial: How to sew a swim bra into a swimsuit

Hey ladies! Want to sew your own swimsuit but need a bit more support than a layer of spandex? Then never fear, because it’s super easy to put a pre-made swim bra into your hand-made suit.

If you’re feeling a little more adventurous, you can even sew your own – check out our Cashmerette Ipswich Swimsuit sewing pattern, which includes a pattern for a full underwired swim bra.

I’m going to share the method I used for my polka dot Bombshell – there are others, including putting elastic in to make a shelf bra (my bust LAUGHS at your shelf bra, but others may be in less need of industrial support), or actually making a swim bra out of foam and bra notions. However I took the easy way: I took a very old and worn out tankini, and seam-ripped the internal underwired bra out, and sewed it into my new suit.

1. Complete your suit to this stage: the front and back are attached, but you haven’t put the straps on yet.

2. Serge (or zig zag) along the top of the suit and lining to join them into one piece.

3. Place your swim bra over the front, making sure the underwire is at least 1/2 inch below the neckline (because you’re going to be folding it over with elastic to finish it). Remember to put it the correct way round, so the softer side will be against your body. I also put the sides of the cups about 1/4 inch beyond the side seam, to avoid too much bulk. Note, your bra may not perfectly match the shape of your suit: no worries!

4. Pin that baby! There was more fullness in the cups than in my suit, so I lightly tucked where necessary and pinned so that it would lie flat to the neckline

5. Stitch it down! Just stitch the neckline, and stop at the edges of the cups – the back strap will be free floating.  I used a narrow zig zag.

6. Trim off the excess if you have any (my swim bra was from a halterneck so had a lot of extra)
7. Now continue with making your swimsuit – the next step in the Bombshell is putting elastic along the neckline.
A couple of things to bear in mind:
– You will want to raise the back of the Bombshell into a less acute curve in order to cover the back strap
– You may also want to change from halter neck to straight straps – that’s super easy, just try on the suit with the bra in, measure the length that you need, make some fabric tubes, and feed bra straps or swimsuit elastic through them.
– Need to grade the Bombshell suit up? You can find my tutorial here.
Hope this is helpful! Let me know if you have any questions.

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How to sew a swim bra into a swimsuit! Tutorial by Cashmerette


14 thoughts on “Tutorial: How to sew a swim bra into a swimsuit

  1. Heather says:

    AAAAND bookmarked, for when I get around to my bathingsuit. If I can find material, that is. 🙂 Thanks for the great tutorial (and hint to scavange a bra from an old swimsuit.

    1. Jenny says:

      I hope it’s helpful Heather!

    2. Ree says:

      @ Heather… has a great selection of swimsuit material!

  2. genius! bookmarking for later for sure. soooo…silly question here. if you don’t have an existing underwire swimsuit to scavenge (prehaps because you got mad at it for fraying and becoming quite seethrough and booted it)…can you use a regular bra (obv. one w/o padding or anything that would hold excess water)? Or does that sound like an excessively problematic idea?

  3. Elaine Day says:

    Thanks for your advice. It was very helpful and wise!
    My Blog: waistcincherhq

  4. Jen says:

    Great tutorial! Where would you purchase a swim bra?

    1. I used one from an old swimsuit – you could see if you could find one in Goodwill. Alternatively you can buy cups from suppliers like Bra Makers Supply.

  5. Anne Reinink says:

    can i sew the bra into the seams right away when making the swimsuit? And then that way not have the back clasp anymore? If so, would the “girls” stay where i need them to? I’d prefer not to have to do the back up every time I wear it.

    1. You won’t get quite as much support, but yes you can definitely do that.

      1. Anne Reinink says:

        I decided to leave the back of the bra attached when making my bathing suit top. I love how mine turned out and it has such great support now. Thanks for your tips.

  6. Jan says:

    How would I add a more supportive bra to an existing swimsuit?

  7. Ali Boncha says:

    FYI The fabric straps link is broken!

    1. T. Williams says:

      Yes, I just tried it and it is still broken (November 17, 2022)

      1. Ayelet says:

        Looks like that site doesn’t exist anymore. I’ve removed the link.

        -Ayelet at Cashmerette

Let me know what you think!