How to Sew a Bikini Top with Braided or Double Straps

DIY Supportive Triangle Bikini Top Without Underwire

If you’re looking for a bikini top that gives both small and big boobs a nice lift without any uncomfortable underwire, this is it!

After reading this post, you’ll be able to make a bikini top that’s supportive, customizable, and so good you’ll want to sew it in every color to wear on repeat!

What You’ll Need to Make a Bikini Top

Let’s get all your materials ready! Whether you’re making the braided version or going for the double-strap look, having the right supplies will make the process smoother.

The Best Bikini Fabric

When choosing your fabric, you’ll want something that can get wet and dry quickly, so it’s best to go with a stretch fabric designed for swimwear.

Look for fabrics like nylon-spandex blends or polyester, as they are durable, moisture-wicking, and comfortable for all-day wear in the sun or water.

Here are 2 options that will help your bikini top maintain its shape and performance, even after a swim or a day at the beach.

Besides the main fabric, I also like to use lining in all my bikinis. It makes them feel softer on the skin, helps them hold their shape better, and just gives the whole thing a nicer, more professional finish.

The Only Elastic I use

For the elastic, I like to use ¼ inch (6mm) swimwear elastic — and I’ve been sticking to the same brand for over 11 years — it’s that good!

It’s soft, stretchy, and made to handle water, sun, and salt without losing shape. It gives just the right amount of support without digging into the skin, which is a big yes in my book!

Must-Have Needles to Sew Bikinis

When it comes to sewing bikinis, a ballpoint needle is a must. I usually go for size 75/11.

If you’ve ever had skipped stitches or weird tension issues while sewing elastic fabrics, switching to a ballpoint needle might just be the fix you didn’t know you needed.

Measuring and Marking Tools

You’re gonna be reaching for these tools a lot while making this top, so it’s worth having them close by.

I love using a measuring tape or a seam gauge (either one works great!), and a washable fabric marker to make little marks

The Bikini Top Sewing Pattern

Before we start cutting and sewing, let’s take a quick look at the pattern. With it you can create both strap styles: braided and double.

Whether you’re a beginner or just love a clear guide, this pattern makes the whole process way easier and less guessy.

DIY tutorial summary

Here are the five essential steps to follow on how to sew a braided-strap bikini top for a flattering lift and cute style. Also, check out the full tutorial below for all the details and sewing tips!

Step #1 – Prepare the Pattern and Cut the Fabric

Print the sewing pattern at 100% scale (check the test square for accuracy) and tape the pieces together, matching letters. Trace your chosen size onto tracing paper if you want to preserve the original.

Cut 2 triangle pieces from stretch fabric, 4 from stretch lining, and the fabric strips for the straps. To make the double straps look: cut 2 pieces of 70 cm strips by 4cm wide. For the Braided Style: cut 6 pieces of 35 cm by 4cm wide.

Step #2 – Create Pad Pockets and join Fabric with Lining

Fold the top point of 2 lining triangle pieces down 3”, pin, and sew 3/8” from the edge with a small zigzag stitch, then trim excess fabric to 1/4” seam allowance.

Place a full lining piece on the wrong side of a fabric triangle, then add the folded lining piece on top, pinning all layers together.

Step #3 – Add Elastic & Stay-Stitch

Sew a straight stitch 1/4” from the bottom edge.

Mark 1.5” down from the triangle’s top tip and 2” up from the bottom edge on both sides to use as starting and ending points for sewing the elastic.

Using a zigzag stitch sew 1/4” elastic between these marks, stretching slightly while sewing. Then, fold the elastic inward, and zigzag stitch again along each side to enclose it.

Step #4 – Make Underbust Strap Channels

Measure 2” up from the bottom edge of each triangle and mark all along the base.

Fold the bottom edge to these marks, pin, and sew the edge with a small zigzag stitch.

Mark the center of the channel (1/2” from the edge) and sew another small zigzag stitch to split the channel into two sections for the underbust straps.

Step #5 – Neck and Underbust Straps

After sewing the fabric strips using my favorite method for making strong bikini straps quickly (find it here!), it’s time to attach them to the top.

For double straps, fold the triangle’s top tip downward, and sew 5/8” from the edge to form a channel. Thread one of the 70cm strips through the channel and stitch the ends to secure

For braided straps, sew one strip 3 cm from the triangle’s top, fold downward, and sew again 5/8” from the edge to form a channel. Pin and sew two strips together. Then, thread them through the channel with a safety pin. Braid, and stitch the ends to secure.

For the underbust straps, use a safety pin, thread through the bottom channels, fold ends 3/8” inward, and sew with a straight stitch for a clean finish.

Watch How to Sew a Bikini Top Step-by-Step

Ready to see it all come together? In this video, I walk you through each step—from cutting the fabric to sewing the straps and adding the final touches.

Whether you’re making the braided version or the double-strap style, this tutorial will guide you through the whole process.

Final Thoughts

Making your own bikinis is such a fun and rewarding experience. Not only do you get to customize every detail, but you also get to wear something that’s uniquely yours.

I hope this tutorial helped you feel more confident sewing your own swimwear—and honestly, once you make one, don’t be surprised if you want to sew one in every color. 🫣

If you’re into that cute and supportive double-strapped look, check out these bikini bottoms with a scrunch back and double bands, they’re one of my favorite combos for a flattering fit.

Let me know in the comments below which one you think you’ll like best: the braided style with its fun texture or the clean and supportive double-strapped look?

Happy Sewing!!