Sewing Swimwear: Tips

When I talk to other people who sew, a lot of them don’t share the same enthusiasm I have for sewing swimwear. The hesitation is understandable. There are definitely some things about sewing swimming suits which take some special planning, skills, and supplies, but with a little practice, you can hit the beach, pool, or sprinkler in your own self-sewn swimwear.

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Pick a Pattern

Obvious, right? Unless you are a stitching wizard and want to jump into swimwear by drafting something yourself, getting your hands on a pattern seems like a logical first step. It just gets a little troublesome when you realize how many lovely swim patterns are out there and you want them all (maybe that’s just me though). The collage above represents five of the patterns I used last summer, and there are plenty more where they came from. And even more coming out this season. I am currently testing a swim pattern that may top my list for a combination of style and ease of assembly, but details on that will have to wait for another post.

There are many factors which may sway you towards one pattern or another, but if you are making your first article of swimwear, the quality of instructions and/or online support can make a huge difference in your sewing experience. Doing a little research on the patterns you like can help you find one (or a dozen) with a style you like and directions which match your sewing skill level.

In case you like the look of any of the suits featured above, here is the rundown:

Top left: 5 Out of 4 Agility Tank

Top middle: Closet Case Bombshell

Top right: Patterns for Pirates Take the Plunge

Bottom left: Closet Case Bombshell (tankini is a modification not included in the instructions)

Bottom middle: Patterns for Pirates Siren Swim Top and Hello Sailor Swim Bottoms

Bottom right: Rad Patterns First Crush


Use Good Fabric

I’m gonna go against the common advice to make a practice version using cheap fabric. I’m all for making muslins, but the lower-quality fabric is often harder to work with. When it comes to swim knit, the good stuff is still pretty squirmy, so anything less than decent is a headache for even the most experienced sewist. Luckily, from the right supplier, one can get quality fabric at decent prices. Over the past year, my stock of swim knit has come mostly from Zenith and Quasar (in the picture above, the only fabric from another source is the feathers), but I’ve also gotten some from The Fabric Fairy and The Purple Seamstress. I’ve also been hearing great things about Made Whimsy and Phee Fabrics, so I plan to try some of their fabric in the next several weeks. If you know of a great swim knit supplier, I’d love to hear about them!

I’ve seen several discussions online about what fiber content to look for in swim fabric. While I’ve historically been skeptical of swim knit that is not nylon/spandex,  Zenith and Quasar‘s yoga swim spandex is a polyester/spandex blend and I love it. The key is really the spandex (aka, lycra) content, which should be at least 20% to provide adequate support, recovery, and stability in water.

Liner Notes

One thing which most people agree on is the need to line swimwear with something. What that something is can vary a little bit. The two commonly recommended options are swim lining and another layer swim knit. For the most part, I have used swim lining. It is thinner and stretchier than swim knit which makes it good for avoiding bulky seam intersections (the picture below shows how thin lining can be). Swim lining is available in a variety of neutral colors, though most of them range somewhere between beige and nude. There is also a variety of textures available, but most are of the smooth, somewhat slick variety. That said, after cutting swim knit, working with swim lining can be a bit of a relief.


Lately though, I’ve mostly been lining with another layer of swim knit. The main reason behind that choice is that the pattern I’ve been testing is engineered to be reversible when lined with swim knit, but I’ve noticed another benefit: more support. The finished product fits slightly snugger than if just lined with swim liner. I know people generally try to avoid things being snug, but in the swim world it can help.

A Note About Powermesh

Many patterns mention the optional use of powermesh. While that can be handy for adding support to bodices and giving a bit of a slimming effect on other areas, the power of powermesh varies a lot. In addition to just being another layer, powermesh gets its power from having less stretch than the main fabric you’re working with. For example, if you’re swim knit has 60% four-way stretch, adding a layer of powermesh with 50% stretch on your stomach panel will hold things in a bit more firmly. Being aware of how stretchy the mesh has will help you decide whether and how to use it. If you find powermesh with a higher stretch percentage, realize that its ability to hold anything in is pretty much nonexistent. On the other hand, if your mesh is too powerful, your garment might not fit correctly (or at least not comfortably).

Cut Cautiously

Yes, you should always cut cautiously. I don’t want you to cut yourself or screw up your fabric no matter what you’re making. But the slippery nature of swim fabric requires a little extra care to help ensure that pieces which are cut accurately. For the most part, I cut only one layer of swim knit at a time. It takes a little extra time to make two cuts to get two pieces, but it makes it more likely that the pieces will be the same. While I have not gone so far as to trace the other half of cut-on-fold pieces to have full-size pattern pieces, I’ve considered it.

Mark the Right Sides

Yesterday I spent way longer than I’d like to admit at my cutting table trying to match up the right sides of four pieces of solid swim knit I had cut without marking the night before. Like many other varieties of fabric, both sides of solid swim knit look similar but are not the same. If you’re anything like me, it’s easier to tell if you put a right and wrong side piece together after the garment is fully assembled, so it is worthwhile to mark the right sides as you are cutting. Just like any other solid fabric though, it doesn’t really matter which side you use as long as you are consistent. With swim solids, one side often has more of a sheen than the other, so all you need to do is decide if you want a slightly shinier or more matte look.


While I used to mark the right side of fabric with safety pins, Mallory Donohue gave a tip which has since changed my sewing life: use painter’s tape. It sticks to most fabric, is easy to remove, and you can write notes on it if you want. I usually write construction notes (right sleeve, outer edge, etc.), but I guess you can write whatever kind of notes you want.

Do a Dry Run

Making a muslin from non-swim fabric can help you become familiar with the pattern before adding the element of slippery fabric. If you’re using fabric with similar stretch and adding in specified elastics and other supplies as needed, you can also get an idea of how the pattern fits you and whether you need to make some adjustments when you make your actual swimsuit. It’s no trouble for me to trim a bit off straps to account for my slightly shorter torso, but if you are on the other end of the spectrum and need to add length, it’d be nice to know that before cutting your pattern pieces. With some patterns, the dry run can be useful on its own. When I first made the Siren Swim Top, I made a muslin from regular athletic fabric and it makes a great lower-impact sports bra.

Embrace Your Standard Sewing Machine

I love my serger. Like, it is perhaps the most stable relationship in my life. But when it comes to sewing swimwear, my standard machine does most of the work. There are a few reasons for this. First off, the slippery nature of the fabric. My serger breezes through the multiple layers of swim and lining, but the layers often slip around a little bit, so the end result is often not up to my standards (which, in many cases, really aren’t that high). With a sewing machine, though, I am able to leave pins in the fabric until the last moment (and in dicey places, can carefully sew over them). That makes it much more likely for the layers to stay in place. Finally, so many steps in the process are done on the standard machine that it is more of a hassle to take the piece to the serger for what bits it can do best. That said, I finish any exposed interior seams in a swimsuit with my serger.

Pin the Bejesus Out of Things

Perhaps it is not the best way of working, but when I’m sewing for myself, I often keep pins to a minimum. But when I’m working on swimwear, the words of my FACS teacher echoes in my head: “Pins are our friends.” And in this case, that statement is really, really valid. Good pinning makes a huge difference in the final product. For the swim bottoms below, I pinned about every inch and a half (and there were a couple places that there didn’t seem like even that was close enough).


Baste All the Things

So, basting to me is like pinning’s big brother. All things are connected, but in this case they are connected in a way you can move around to look at. Most patterns include references to basting places, but it’s not a bad idea to baste pretty much everything. I have to unpick more things in swimwear than anywhere else. Not only does basting make it more likely that your pieces come together accurately, but if they don’t, basting stitches are easier to rip out than, say, a serged seam. Unless the pattern specifies otherwise, when I baste swimwear, I use a long, somewhat narrow zig-zag stitch.

Working with Elastic

One of the most challenging things for many people new to swimwear is the issue of elastic. There may be a way to make a swimsuit without elastic, but I can’t imagine actually doing it myself. There are a few things you want to keep in mind when selecting elastic. First off, there is a difference between regular elastic and swimwear elastic. Swimsuits not only need to stretch and support more than the average garment, regular elastic is not going to last as long when repeatedly exposed to chlorinated water (I’ve also heard that salt water also degrades swim elastic faster, but that’s not really an issue I’ve encountered in Missouri).

There are at least a few kinds of elastic often used in swimwear. Clear elastic (lastin) can be used in some applications and is less bulky than other types of elastic, but I have only seen it available in narrow widths. There are both rubber and cotton-based swimwear elastic which are supposed to last longer in swim applications. I keep a big spool of 1/4″ swim elastic in my supplies as I use it throughout the year for more than just swimwear (I find it easier to work with and more comfortable than regular elastic). I also keep a stock of 3/8″ cotton swimwear elastic on hand as that is another commonly used size (and the only size I can purchase locally). Many patterns, though, call for wider elastic, and that is when I turn to a supplier who stocks a wide range of swim elastic (The Fabric Fairy is my current go to for that).

For best results, exercise that elastic a few times by stretching it before measuring and cutting. In most cases, I baste fabric layers together before attaching elastic (unless the pattern requires you to do something different). If you find applying elastic to be difficult, you might need more pins or more patience, but chances are it is just a little more experience that will do the trick.

Learn the Art of Understitching

When I sewed my first few swimsuits, I had no idea what understitching was. Someone in a pattern group on Facebook suggested it as a way to help with a particular issue I was having, and Google led me to some good descriptions, illustrations, and videos to learn about it. Basically, understitching is sewing the seam allowance to the lining. The result is that when turned right side out, the lining side pulls more and makes the main fabric be along the edge instead of meeting the lining there and being more noticeable. So far, I’ve only used understitching along necklines, but I suppose it could have some good applications elsewhere.

Do It Again

You could be amazingly skilled and come up with a fantastic swimsuit on your first attempt. Or you could be like me and come up with a decent result which you aren’t quite satisfied with. Or it could be an utter unwearable disaster. Regardless, do it again. The second swimsuit is easier. And the third. And the fourth…


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