How to Make a Swimsuit with Breast Support (Sewing a Bra Tips) Update 05/2022

The absence of bust support in off-the-rack swimsuits is a source of unhappiness for many women. A lack of support in the critical area might let you and the suit down, no matter how nice the outfit is.

Fortunately, a little deception and some simple sewing abilities may be all you need to completely transform your swimwear… and your physique.

How to Add Breast Support to a Swimsuit (Sewing a Bra Tips)

Adding boning, underwiring, and/or cups is a simple process that doesn’t involve any special skills or needle proficiency. However, before you get started, it’s a good idea to perform some preliminary study about the various options.

How to Add Support to a Swimsuit

While some alternatives will improve your shape (and who would argue with a bit extra shape and a more appealing silhouette? ), others are excellent for giving support (thereby being a must-try for ladies with a fuller-figure).

Whether you’re seeking for full coverage and maximum support, or just a bit more modesty and a better shape, you’ve come to the perfect place.

How to Add Boning to a Swimsuit

Boning is your best bet for getting a little support and a lot of shaping. Boning can be readily added to your swimsuit template as long as it has a side seam.

Adding Boning to a Bikini top Pattern

Make the top according to the instructions. Sew a second seam of the same length about 14 inch distant from the first once the side seam is finished. Cut a piece of plastic boning a bit shorter than the vertical channel you just sewed and round the ends. Before continuing with the rest of your pattern, insert the boning into the channel.

Adding Boning to a One-Piece Pattern

Repeat the steps above, but after stitching the channel’s bottom edge, finish it off with a sequence of horizontal stitches.

Adding Boning to a Rady-to-Wear Swimsuit

To make a lining “tube,” cut a small strip of swimsuit lining and sew it to the inside of the suit at the side seam. Close the lining at both ends and insert the boning.

Adding Underwire to a Bathing Suit

Underwiring is one of the finest ways to ensure that your swimwear has plenty of support. The approach below is easy to follow and works with almost any swimsuit pattern. If you can’t find any of the required materials in a fabric store, they’re frequently accessible online.

What You’ll Need

  • Power Net
  • A Set of Underwires
  • ​Bra Channeling
  • Fabric Pen

The Method

  • Make a front and back bodice out of the power net. On the wrong side of the net, mark the center front.
  • Make the channeling an inch longer than the underwiring.
  • Trace the shape of the underwire onto the power net with a fabric pen. Place the wire 12 inches from the front line’s center and 1 inch from the bottom edge.
  • Draw a 14-inch extension from the existing lines on the side closest to the center, and a 12-inch extension on the other side (the result should be proportionate to your bust size: if you have a larger bust, you may need to angle the lines out a little further).
  • Baste the channeling in place along the line, leaving a 12 inch gap on either side.
  • In the channels, place the underwiring. If your wiring has a colored tip on one side, feed it through the slot with the colored tip nearer to the front center. Make sure the wire is fed through the channeling rather than the space between the power net and the channeling.
  • Sew the swimsuit’s side seam and try it on to make sure it fits. The wire should sit just below your bust, flush against your body.
  • Remove the wire from the channeling and sew the sides to seal the edges if the underwiring fits properly. Close the center front edges by stitching a bar tack over the ends of the channeling.
  • Replace the other wire and repeat the operation. Trim the channeling as close as feasible to your stitching line.
  • Run the wire through the channeling and use the same process to seal the opposite side of the channeling.

Adding Bust Support to a Swimsuit: Boning & Cups

How to Put an Underwired Bra in a Bathing Suit

There’s an easy option if you want the added support of underwire but don’t want to put in the effort of the previous method (or if you want to add it to a ready-to-wear item rather than a swimsuit you’re creating yourself).

The Approach

  • Cut an underwired bra in half down the center. Remove all straps and decorations.
  • Cut two ‘X’ shapes in the front lining of the swimsuit where you want the bra cups to go (the size of the Xs will depend on your bust size). Pin the bra cups in place after pushing them through.
  • Sew the swimsuit liner to the cups, being careful not to stitch over the underwiring.
  • To finish, trim away any excess lining fabric.

How to Sew a Bra in a Swimsuit

Sewing a bra into your swimsuit is a terrific idea if you want full support and a lot of coverage. Simply grab any old bra from your closet (though you’ll want to make sure it’s one that provides adequate support and comfort). If it contains foam cushioning, check to see if it’s water-resistant first; otherwise, you’ll have to wring yourself out after each plunge), then gather your sewing supplies and follow this simple guide.

The Approach

  • Finish the swimsuit according to your pattern, but stop just before the front and back are joined but the straps haven’t been added. Sew the fashion material to the lining along the top with a serger or zig-zag stitch to produce one piece.
  • Cut the strap above the cups and behind the bra band. Trim any embellishments off the bra that might interfere with the swimsuit’s smooth line.
  • Place the bra, skin side out, over the front of the swimsuit. Position the bra such that the underwire is at least 12 inches below the neckline if it has underwiring. Pin to keep everything in place. You may need to add a few darts if the cups are bigger than the suit to achieve a neat finish.
  • Sew down the neckline with a narrow zig-zag thread, leaving the back of the bra free-floating.
  • Trim any excess to ensure the bra isn’t visible over the swimsuit’s neckline.
  • With the bra half completed, you may move on to the rest of your pattern.

Sewing Cups Into a Bathing Suit

One of the simplest methods to add more comfort and support is to sew cups into a swimming suit. To get started, all you’ll need are some basic sewing supplies and some bra cups.

Because the process varies depending on whether you’re attaching the cups to a ready-to-wear swimsuit or one you’re making yourself, be sure to read the following directions carefully (although for both methods, the prep stays the same).


Choosing the Right Cups: Bra cups are available at most fabric and craft stores. If you want to save a few dollars, go to your local thrift store and look for a swimsuit from which you may salvage the existing cups.

A soft cup will suffice if you’re adding cups primarily for modesty rather than support. Look for a foam cup if you want the best of both worlds (but be sure it won’t soak up water like a sponge the second you get in the pool before you put it in your swimsuit). The more seamless, lightweight, and water-resistant cups you can locate (some will even be branded ‘for swimwear’), the better.

Choosing the Appropriate Cup Size: Unlike bras, where finding the right size is an exact science, swimwear bra cup sizes can be a little more relaxed. Cups are frequently sliced across dimensions (A/B, B/C, and so on). Going slightly larger than your typical size is usually the best way to keep the cups firmly in place; for example, if you’re usually a B cup, go for the B/C size instead of the A/B, and so on.

Sewing Bra Cups Into Ready-to-Wear Swimsuits

  • Cut a small slit in the swimsuit’s lining.
  • Pin the cups in place after inserting them through the perforations.
  • Try the suit on (carefully avoiding the pins) and make any required modifications to attain the perfect fit. To fasten, add a couple more pins.
  • Starting at the bottom of the edge cup and working your way around the edges, sew the cups in place.

Sewing Bra Cups Into Swimsuit Patterns

As you sew the suit, just slip the cups between the cloth and the lining. Some suits will be designed so that the cups will stay in place on their own; others may require assistance. Try the suit on and see how the cups fit once you’ve added the cups. Pin the cups in place, remove the suit, and tack them in place if you think they need further support.

How to Add Breast Support to a Swimsuit (Sewing a Bra Tips)

How to Increase Modesty Without Support

Simply cut out several layers of lining fabric, stitch them together to create one piece, and sew in place around the inner front of your bathing suit if you desire modesty but don’t require the support of a real cup. This is a quick solution for smaller-chested girls to maintain their modesty after a dip without the bulk or unneeded support of cups.

Sewing With Swimsuit Material

Knowing how to work with swimsuit fabric is useful whether you’re adding cups, bras, boning, padding, or anything else to your swimsuit. Sewing with swimsuit fabric (or, really, any kind of material that’s designed to put the’streeeetch’ in stretch) may be difficult even for the most experienced craftsman. Fortunately, this isn’t the case. If you follow a few simple guidelines, you’ll no longer be afraid of Lycra.

Choose Your Fabric Wisely

Swimsuit material is usually divided into two categories: two-way stretch and four-way stretch. 2-way stretch cloth can only stretch horizontally. Fabric with 4-way stretch expands both horizontally and vertically, so it will stretch around the body as well as up and down it. To avoid a disappointing result (not to mention a more difficult sewing experience than necessary), be sure the cloth you chose is suited for your pattern.

Use the Right Equipment

You’ll want to make sure your equipment is up to the task if you’re working with stretch materials. Never use anything other than stretch needles, and always use polyester thread over cotton.

Choose The Right Stitch

A traditional zig-zag stitch or a triple zig-zag stitch both work well for basting or adding elastic to the swimsuit fabric. Choose the triple straight stitch, stretch stitch, or lightning stitch if you need a straight line of stitches.

Practice Makes Perfect

If you’re new to sewing with stretch fabric, test several stitching kinds and procedures on a scrap of spare material to calm your nerves before tackling the swimsuit. To get a feel for working with layers, fold the cloth in half and practice a few seams. You’ll undoubtedly feel much more confident by the time you start on the swimwear.

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