Swim Trunks

Welcome to Celebrate the SUMMER Boy week!..both here on MADE and over on Made by Rae.
I thought we’d kick it off by heading to the pool….since we swam four times last week in our 100 degree weather.
The past two summers I’ve made swimsuits for Lucy. But until this weekend I’d never made the boyish version. And now I’m wondering why I waited this long.

Using the Kid Pants/shorts pattern it’s easy!
And with the Diaper Cover pattern, you have the option of adding a mesh lining inside:
Owen’s ready to hit the pool!
The only drawback to this project is that swim trunk fabrics are not very accessible. For such a simple/common store-bought item, you’d think there’d be more fabric options in the shop.
But press on! We’ll talk about some online fabric resources. Then I’ll use an existing pair of men’s trunks to refashion them down to smaller trunks, walking you through all of the steps so you can make your own too.
Let’s get started!

My original plan was to show you how to make swim trunks from scratch, using the KID pants pattern. But that same old question kept bubbling up, “where do you buy nylon/polyester swim trunk fabric??” I wish I had better news. Most swim trunks are made of a soft, thin quick-drying polyester, with a nylon mesh lining. The fabric is nothing special. But I can never find it in my local fabric shop. And nylon ripstop doesn’t cut it. It’s too see-thru and crisp. So, I searched online and found these…

Online shops:
* Fabric Fairy – they carry about seven board short prints!
* Seattle Fabrics – good spot for mesh fabrics
* Sundrop – someone recommended this though I can’t find a specific fabric that catches my eye.
* Spandex World – this is my go-to shop for girl’s swimsuit fabric, or if you want to make your little man a speedo! (check out this totally cute speedo/trunks rendition by Rae).

For more info on Spandex World and sewing with spandex, check out my Tips for Making a Swimsuit Tutorial:
If you have a great go-to swim trunks fabric shop, please leave info in the comments!

So, I went with my next best option: swim trunks refashion. I bought men’s tunks from the thrift stop. Some of you might cringe at that. If it’s not your thing, I totally get it. I washed them though and feel okay with it. In fact, some thrift shops carry new swim trunks too.
I couldn’t decide which I liked most so I bought three pairs but went with the brown because they were easiest to cut apart and I liked the front stripes.
If you’re making trunks from scratch and would like similar curved stripes:
Create single-fold bias tape (using our Bias Tape Tutorial) and then form/sew them to your fabric–assuming you’ve found some polyester trunk fabric.

We’ll be using two patterns for our swim trunks:
* KID Shorts (a version of the KID Pants) – I’m using the Flat Front version
* The Perfect Diaper Cover (for the lining)
Start by cutting the existing trunks into smaller trunks. If the trunks don’t have a sideseam like the brown trunks, you can incorporate that into the new trunks. I originally planned to do that. But it became complicated with the stripes continuing around to the back and I wanted use the existing hem of the shorts, so I decided to chop the whole thing up and make an entirely new pair.

Lay your pattern over the top and trace/cut out the new pieces.. If you’re using the existing hem, remember to account for that in your cutting. Cut them a bit shorter than you normally would.
And you end up with four pieces like this (2 front, 2 back):
Pin and sew your shorts, as outlined in the Kid Pants tutorial. First the two crotch areas, then the inseam, then the side seams. Stop when you get to the waistband so we can add-in the lining.
For a cool “board shorts” look, top-stitch on the right side of the fabric with a contrasting thread color. It’s easiest to topstitch after each step above (rather than deciding to do it at the end…when the shorts are entirely sewn, like I did). Use the line of the seam and your presser foot to guide you in a straight line. Sew another parallel line next to the first for a double-line look (you can also use a double needle for this but I’m too lazy to unscrew the needle and rethread).
Adding a mesh undies lining is optional. If you hate em, leave it out. If you want it, read on.

To create the lining you have a couple options…
* Buy mesh fabric and use the Perfect Diaper Cover pattern/tutorial to create the lining. Size the pattern up if needed and don’t finish the waistband.
* Use an existing liner from another pair of swim trunks and size it down. This is what I did.
Cut the lining out of existing trunks and cut the sides open so you can access the front and back separately. It’ll look like a diaper. Fold it in half and lay the front shorts pattern over the front portion of the lining. Line up the shorts crotch with the lining crotch seam and cut around the pattern–so that the lining fits fairly close to the size of the trunks. It won’t be exact but that’s perfectly fine. Do the same thing for the back of the lining,with the Back of the shorts pattern.
When you’re done, you have a smaller version of the original lining. Sew down the side seams and leave the waistband unfinished.
With the lining turned inside out, stuff it inside of the trunks and pin it in place next to the trunk’s waistband. The lining may be a bit larger and slightly bunchy here or there. Try your best to evenly spread the mesh fabric around. Move more of the bunchy-ness to the back of the trunks where the elastic waist will be. Then baste (sew together) or serge the lining and trunks together at the waistband.
Then fold/iron over your waistband and insert the elastic (remember you’re only using elastic in the back of the swim trunks if you’ve created the flat front version ). I used standard polyester elastic from Joanns. Swim/rubber elastic will withstand chlorine better but I was antsy to get started….and I’ve used standard elastic in the past and it’s been fine.
When you’re done, you’ve got a pair of flat front swim trunks! As you can see my front got a bit bunched up. I tried my best but sometimes it happens. So let’s cover it up with one added touch….
Remove the tie and fabric flaps from the old swim trunks.
Or you can make your own:
Using leftover fabric from the old trunks, cut and sew double-layered rectangles, turn them right side out, and finish off the edges (similar to the flaps below). Then pound four small grommets into the flaps.

These flaps are a bit too wide for my waistband but eh, it’ll work. Pin them in place leaving about a centimeter of space in-between. Sew them down, then pin/sew the middle of the tie to the middle of the waistband (so your little guy doesn’t lose the tie somewhere)
And you’re done! A new pair of swim trunks!
with a snazzy mesh liner:
I absolutely love them. And Owen does too. He’s obsessed with the color orange and was happy to see those colorful stripes.
Summer has officially begun!
Check out Rae’s cute bucket hat over on Made by Rae:

  1. 2) Jessie

    cool! I’d like to find a tutorial on how to take a pair of men’s board shorts and turn them into low rise women’s board shorts (keeping a long inseam)

    • 3) Lls

      Just curious… Did you ever find a pattern/ tutorial on modifying into women’s? I just found this post while looking for that.

  2. 4) Laura

    I’ve been searching for a free board shorts pattern for hours now, and i think i might just go with this one. A little disappointed that you used already made shorts and just adjusted the size to fit your little one, which makes my job even harder…lol
    The problem is I will have to adjust the pattern for the adult size 33, as i’m trying to make them into a surprise trunks for my boyfriend. He fits approximately the same size of bottoms as me, so at least i will be able to try it on.
    I found some nice sewing patterns online, but they are $10+. Then you have to include the price of a fabric and other necessary things for this project = and your final price will be more than what you would pay for a nice pair in store.
    So i hope i will be able to tackle this task with a help from your blog. My boyfriend really loves his board shorts, so i want to make a special pair for his collection.
    Wish me luck 🙂

  3. 5) Ashley

    This is wonderful! My 5 year old got a burn on his calf and of course cannot get any sun on it. I am going to do this but make them into pants. Then he can still enjoy the sun and the water. Hopefully I can make them turn out well!

  4. 6) Natasha

    Great tutorial! I am making a swim skirt and want to line it with mesh to cut down on cling. I found Seattle Fabrics online but I’m clueless which type of mesh would work best. Any ideas? Thanks!

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  6. 8) Katherine Burke

    Your website link for mesh has athletic mesh and sports mesh. Which do you think is closer to swim trunk mesh?

    • 9) Dana

      I actually used the mesh that came in the men’s swimsuit and then cut it down to fit my diaper cover pattern.

  7. 10) Fam

    Hello there:

    Thank you for your pattern and details. I would like to know if you have done any other pattern in video or all are written down.
    Any ideas where I could purchase materials for pants and swimming suits or even surfing shirts?
    Thank you for everything

  8. 13) Majella

    What a great blogpost.
    I like it. I gonna make this for my boy.

  9. 14) Christine

    Woohoo! So happy to find this. My husband has lost a bunch of weight and I want to transform his too big swim trunks into board shorts for him and my sons out of the old ones. This is perfect! I took the first pair apart last night!

  10. 15) Kristyn

    I currently purchased a pair of swim trunks for my future brother-in-law with pictures of my sisters Face on them unfortunately I found out there’s no lining in the trunks my brother-in-law won’t wear them if there are not any lining in them I read through your article and I visited some of the websites I’m just unsure for men he is a size Large and the trunks I purchased so what fabric would I purchased to put in the shorts and how much I’ve never done this before I have a mother-in-law that can sew But I don’t know if she even knows where to get the fabric any feedback would be greatly appreciated thank you

  11. 16) Dyl

    Hey I absolutely love those white swim trunks with the side stripes. I don’t really know how to sew and I realize this is an old website, you say it’s kid size but, I know it’s a long shot, but would you be interested in making an adult one?

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