Free Crochet Bikini Pattern with Adjustable Straps

If you’ve been searching for the perfect summer project, this free crochet bikini pattern with adjustable straps is exactly what you need. Whether you’re a seasoned crocheter or someone who’s confident with the basics and ready to try something a little more adventurous, this pattern is designed to be approachable, customizable, and genuinely wearable. By the end of this post, you’ll have everything you need to create a beautiful handmade swimsuit top and bottom that fits your body perfectly — because adjustable straps mean you’re not locked into one size.

Handmade swimwear has had a major comeback in recent years, and for good reason. When you make your own bikini, you control the coverage, the color, the yarn, and the fit. No more settling for a top that gaps at the cups or a bottom that sits too low. This pattern gives you full creative control while keeping the construction simple and logical.

Let’s dive in.

What You’ll Need Before You Start

Before picking up your hook, gather your materials. Having everything ready saves time and helps you work through the pattern smoothly.

Materials List:

Cotton yarn is the gold standard for crochet swimwear. It dries quickly, holds its shape when wet, and doesn’t stretch out the way acrylic does. Look for a worsted weight (size 4) or sport weight (size 3) cotton yarn depending on the look you want. Sport weight creates a more delicate, swimwear-like fabric, while worsted gives more coverage and body. For this pattern, a sport weight or DK weight cotton is ideal. You’ll need approximately 300–400 yards for the top and 200–300 yards for the bottom, depending on your size.

A 3.5mm or 4mm crochet hook works well with sport or DK weight cotton. Always check your gauge swatch before starting, especially for swimwear where fit is everything.

You’ll also need a yarn needle for weaving in ends, scissors, measuring tape, stitch markers, and optional underwire or bra cups if you want additional support in the top.

Gauge:

For this pattern using sport weight cotton and a 3.75mm hook, aim for approximately 18 stitches and 20 rows per 4 inches in single crochet. Take the time to swatch. It makes a bigger difference than you might expect.

Sizing Guide

This pattern is written for sizes XS through XL. Because the straps are adjustable and several sections are built to be modified, the fit is flexible across a wide range of bodies. Here are the approximate finished measurements you’re working toward:

The bust measurement for XS is 30–32 inches, S is 32–34 inches, M is 34–36 inches, L is 36–38 inches, and XL is 38–40 inches.

For the bikini bottom, the hip measurement guides your sizing: XS is 32–34 inches, S is 34–36 inches, M is 36–38 inches, L is 38–40 inches, and XL is 40–43 inches.

Throughout the pattern, instructions for each size are written as XS (S, M, L, XL). When you see a number followed by numbers in parentheses, the first number is for XS and the numbers inside correspond to S, M, L, and XL in that order.

Abbreviations Used in This Pattern

ch — chain
sl st — slip stitch
sc — single crochet
hdc — half double crochet
dc — double crochet
sk — skip
sp — space
rep — repeat
RS — right side
WS — wrong side
st(s) — stitch(es)
beg — beginning
rnd — round
rem — remaining

Part One: The Bikini Top

Understanding the Construction

This bikini top is worked in two triangular cups that are joined at the center, with a band that wraps around the body and ties or adjusts at the back. The straps go over the shoulders and can be lengthened or shortened by simply crocheting more or fewer chain stitches, or by adding adjustable loops. The triangle construction is one of the most flattering and versatile shapes for a crochet bikini top because it naturally accommodates different cup sizes.

Making the First Triangle Cup

The cup begins at the bottom point and is worked upward in rows, increasing on each side to create the triangle shape.

Foundation: Chain 3, join with a slip stitch to form a ring, or simply chain 3 and work into the third chain from the hook if you prefer a less visible starting point.

Row 1 (RS): Work 3 sc into the ring or starting chain. Turn. (3 sts)

Row 2: Ch 1, 2 sc in first st, sc in next st, 2 sc in last st. Turn. (5 sts)

Row 3: Ch 1, 2 sc in first st, sc across to last st, 2 sc in last st. Turn. (7 sts)

Continue in this manner, increasing one stitch at each end of every row, until you have 29 (31, 33, 35, 37) stitches on your needle.

Work 2 (3, 4, 4, 5) more rows even without increasing, keeping in single crochet throughout. This creates the flat upper portion of the cup.

Fasten off, leaving a long tail for seaming.

Make a second cup identical to the first.

Joining the Cups

Lay both cups flat with right sides facing up. Hold the two cups together so they mirror each other, with the center edges touching. Using your yarn needle and a length of yarn, whipstitch or mattress stitch the two inner edges together. This seam forms the center front of your bikini top.

Alternatively, you can join them with a row of slip stitches using your hook, which creates a slightly more finished appearance on the right side if done carefully.

Adding the Band

The band runs along the bottom of both cups and extends outward on each side to wrap around your torso and tie at the back.

With the RS facing and your hook, attach yarn at the bottom right corner of the right cup. Work a row of single crochet across the entire bottom edge of both cups, picking up stitches evenly. You should have approximately 50 (54, 58, 62, 66) stitches across the base.

Now you’ll extend the band on each side. At the end of this row, chain 60 (65, 70, 75, 80) stitches. This becomes the tie on the right side. Fasten off.

Rejoin yarn at the bottom left corner of the left cup and chain 60 (65, 70, 75, 80) stitches for the left tie. Fasten off.

Work a row of sc back along each tie and across the full bottom band for a neater, more polished finish. This also adds a little structure to the ties so they don’t feel floppy when worn.

Adding the Neck Straps

The neck straps attach at the top outer corners of each cup and tie behind the neck, which is where the adjustability really comes into play.

Attach yarn at the top outer corner of the right cup. Chain 70 (70, 75, 75, 80) stitches for the strap. Work sc back along the chain for a finished strap. Fasten off.

Repeat on the left cup.

If you want truly adjustable straps rather than tie straps, you can crochet a longer strap on one side and add a small loop or buttonhole on the other side that the strap threads through before tying. This allows you to shorten or lengthen the strap while wearing the top without having to retie it every time.

To make the adjustable loop: At the attachment point on one side, chain 10, skip 4 stitches, and slip stitch into the next stitch. This creates a small loop. The strap from the opposite cup threads through this loop and ties off, giving you a slider-style adjustment point.

Finishing the Top

Weave in all ends thoroughly. Cotton yarn can be a little slippery, so make sure your ends are secure — going back through the stitches in multiple directions helps. If you’re adding bra cups for support, hand stitch them into the inside of each cup using a needle and thread in a matching color. Cups can be found at fabric stores or ordered online and make a significant difference for comfort and shape.

Part Two: The Bikini Bottom

Understanding the Construction

The bikini bottom is worked from the crotch gusset upward in joined rounds to form the front and back panels. The sides are either left open and tied, or seamed depending on your preference. For adjustable fit, this pattern leaves the sides open with tie closures, which also adds a nice visual detail.

Making the Gusset

Chain 16 (18, 20, 22, 24). This forms the base of the crotch.

Row 1: Sc in second chain from hook and in each chain across. Turn. (15, 17, 19, 21, 23 sts)

Rows 2–6: Ch 1, sc across. Turn.

This rectangle becomes the foundation for the front and back panels.

Working the Front Panel

With RS facing, pick up stitches along one long edge of the gusset. You will work upward in rows to form the front panel, increasing at each side every other row to create the hip shaping.

Row 1: Attach yarn at corner, sc evenly across the long edge of the gusset, picking up approximately 15 (17, 19, 21, 23) stitches. Turn.

Row 2: Ch 1, 2 sc in first st, sc across to last st, 2 sc in last st. Turn. (17, 19, 21, 23, 25 sts)

Row 3: Ch 1, sc across. Turn.

Repeat Rows 2 and 3 until you have 31 (35, 39, 43, 47) stitches.

Work even for 8 (9, 10, 11, 12) more rows without increasing. This forms the main body of the front panel.

Fasten off.

Working the Back Panel

The back panel is worked the same way on the opposite long edge of the gusset, following the exact same instructions as the front panel. The back panel typically has a little more coverage, so if you’d like more fabric at the back, you can work 2–4 additional rows even at the top before fastening off.

Adding the Side Ties

Side ties are what make this bottom fully adjustable at the hips. They also allow you to customize the rise and coverage easily.

At the top corner of the front panel, attach yarn and chain 50 (55, 55, 60, 60) stitches. Work sc back along the chain. Fasten off. Repeat at the other top corner of the front panel, then at both top corners of the back panel, so you have four ties total — two on the front and two on the back.

To wear, simply bring the front and back ties on each side together and tie in a bow at the hip. The length of the chain gives you plenty of room to adjust the positioning and tightness to suit your body.

Adding the Waistband

For a more polished look, work a row of sc along the entire top edge of the front panel, across the top of one side, along the top edge of the back panel, and back down the other side, creating a continuous edging. This keeps the top edge neat and prevents rolling or curling, which cotton yarn can sometimes do.

You can also work this round in crab stitch (reverse single crochet) for a decorative twisted edge that looks very professional.

Finishing Touches and Care Tips

Once both pieces are complete, give the entire bikini a gentle hand wash in cool water with a mild detergent. Lay flat to dry — never put a crocheted swimsuit in the dryer. This is especially important for cotton, which can shrink and tighten under heat. When the pieces are slightly damp, you can gently block them into shape, which is particularly helpful if the cups or panels look a little uneven after joining.

Blocking a crocheted swimsuit simply means pinning it to a foam mat or towel in the correct dimensions and allowing it to dry in that shape. It makes a dramatic difference in how finished and professional the final product looks.

Always store your handmade bikini flat or loosely rolled rather than folded, to preserve the shape of the cups.

Customization Ideas

One of the best things about making your own swimwear is how easily you can personalize it. Here are a few ideas to make this pattern your own.

Color blocking is incredibly popular in handmade swimwear right now. Try working each cup in a different color, or making the bottom panel a contrasting shade to the ties. Even alternating two colors every few rows in the cups creates a beautiful striped effect.

Shell stitch edging along the top of the cups or around the leg openings of the bottom adds a delicate, feminine look that photographs beautifully.

Metallic thread held alongside your cotton yarn creates a subtle shimmer that’s perfect for a resort-style look. Use it sparingly — maybe just on the edging or ties — for the best effect.

Fringe ties are a fun boho option. Instead of plain chain ties, work your straps as usual and then add short lengths of yarn at regular intervals along the tie for a fringe effect. This looks especially good on the hip ties of the bottom.

Adding a ring or D-ring at the center front of the top, where the two cups meet, gives a hardware detail that feels very modern and chic. Simply crochet around a small brass or gold-colored ring before joining the cups, and it becomes a focal point of the design.

Common Questions About Crochet Swimwear

Will the yarn stretch out when it gets wet? Cotton yarn holds its structure far better than other fibers when wet, which is why it’s the standard choice for crochet swimwear. Avoid acrylic entirely for swimwear — it can stretch significantly when saturated and won’t return to its original shape. If you want extra security, you can line the cups with swimwear lining fabric, which is available at fabric stores.

How do I know if my gauge is right? Wash and dry your gauge swatch before measuring it, so you’re accounting for any shrinkage the yarn might have. If your swatch is larger than the gauge calls for, go down a hook size. If it’s smaller, go up a hook size.

Is this pattern suitable for beginners? This pattern uses only basic stitches — single crochet and half double crochet — so the stitch work itself is beginner-friendly. The shaping and construction require a little more attention, so it’s best suited to someone who is comfortable with crocheting in rows, increasing and decreasing, and reading a pattern. If you’ve completed a few projects and want a step up, this is a great choice.

How much yarn do I actually need? The yardage depends significantly on your size and how many colors you use. For a solid-color set in size medium, plan on 500–650 yards total. Buy a little extra — it’s always better to have leftover yarn than to run short mid-project.

Final Thoughts

A handmade crochet bikini is one of those projects that gets you so many compliments when you wear it. There’s something genuinely satisfying about wearing something you made yourself, especially when it fits better than anything you’d find in a store. The adjustable straps in this design aren’t just a practical feature — they mean this bikini works for real bodies in all their variety, and can grow or change with you over multiple summers.

Take your time with this one. Work a swatch, measure twice, and don’t rush the finishing. The extra care you put into weaving in ends and blocking the finished pieces pays off enormously in how polished the final result looks. And when you’re done, you’ll have a truly one-of-a-kind swimsuit that’s completely yours.

Happy crocheting, and happy summer.