How To Crochet A Bikini Bottom The Right Way For All Sizes
Whether you’re a seasoned crocheter or someone who’s just mastered the basic stitch, making your own crochet bikini bottom is one of the most rewarding warm-weather projects you can take on. Not only do you get a swimsuit that fits your body perfectly, but you also get to choose exactly the color, yarn, and style that suits you best. The problem most people run into is that free patterns online are often sized for one body type, leave out key details about shaping, or don’t explain how to adjust for different measurements. This guide is here to fix all of that.
By the time you finish reading, you’ll understand which materials to use, how to take your measurements correctly, how to work the pattern from the waistband to the gusset, and most importantly, how to modify every step for any size — from XS to 4XL and beyond. Let’s get into it.
What You Need Before You Start
Getting the right materials makes a significant difference in how your finished bikini bottom looks, fits, and holds up in the water. Here’s what to gather before you cast on.
Yarn: Choose a cotton or cotton-blend yarn specifically made for swimwear, or look for yarn labeled as “quick-dry.” 100% cotton yarn like Lion Brand 24/7 Cotton or Paintbox Simply DK Cotton work beautifully. Avoid wool entirely (it soaks up water and gets heavy) and be cautious with acrylic (it can become slippery and doesn’t breathe well against skin). A mercerized cotton gives you a slight sheen that looks polished poolside.
Hook Size: Most cotton DK or sport weight yarns pair well with a 3.5mm to 4.0mm hook. Always go slightly tighter than the yarn label suggests, because a looser fabric means more stretch when wet, which can lead to unexpected revealing moments in the pool. Your gauge swatch will tell you exactly which hook size to use.
Elastic: A ¾-inch or 1-inch braided elastic works best for the waistband. Cut it to your comfortable hip measurement minus a few centimeters, since it will stretch over your hips when you put the bikini on. Some people prefer soft fold-over elastic at the leg openings as well, but this is optional depending on the style you’re going for.
Stitch Markers: These are essential for keeping track of your beginning-of-round, your increases and decreases, and where your gusset begins and ends.
Tapestry Needle and Scissors: For weaving in ends and seaming any pieces together.
A Measuring Tape: You’ll need this throughout the process, not just at the beginning.
Taking Your Measurements Correctly
The key to a crochet bikini bottom that fits every body well is accurate measurements. Don’t skip this step or eyeball it — a few centimeters off can mean the difference between a bikini that flatters and one that gaps, sags, or digs in.
Take these four measurements:
Waist: Measure around your natural waist, which is the narrowest part of your torso, usually just above your belly button. Keep the tape measure snug but not tight. Write this number down.
Hips: This is the widest part of your lower body. For most people, this falls about 7 to 9 inches below the natural waist. Measure at the fullest point of your hips and buttocks. This is typically the largest measurement and the one that governs how big your bikini bottom needs to be.
Rise: This one is crucial and often overlooked. The rise is the distance from your waist in front, down through the crotch, and up to your waist in the back. Sit on a chair to take this measurement, running the tape between your legs. This determines how much length your gusset needs.
Leg Opening: Measure the circumference of your upper thigh where you want the bikini leg to sit. This helps you figure out how open your leg holes need to be so they’re comfortable without gaping.
Keep all four numbers on a piece of paper next to you as you work.
Understanding Gauge and Why It Matters More Here Than in Other Projects
Gauge is always important in crochet, but for swimwear it’s non-negotiable. Unlike a blanket where being off by a stitch or two just changes the dimensions slightly, a bikini bottom needs to fit a specific body. Additionally, cotton yarn behaves differently wet versus dry, and it tends to have very little give. Getting your gauge right means your finished piece will match the dimensions you’re aiming for.
Make a gauge swatch at least 6 inches by 6 inches in the stitch you plan to use for the main body of the bikini. Single crochet is the most common and gives a dense, stable fabric that holds its shape well. Half double crochet creates a softer drape if you prefer that feel.
Measure your swatch after it has been washed and dried (or at least dampened and blocked), since cotton fabric relaxes when wet.
A standard gauge for DK cotton on a 3.75mm hook is approximately 18 to 20 stitches and 20 to 22 rows per 4 inches in single crochet. Your gauge will determine how many stitches you cast on and how many rows you need to work to hit your measurements.
To calculate your stitch count for the waist: divide your waist measurement (in inches) by 4, then multiply by the number of stitches per 4 inches in your gauge. That gives you your starting chain count for the waistband.
For example, if your waist is 32 inches and your gauge is 18 stitches per 4 inches: 32 ÷ 4 × 18 = 144 stitches.
The Basic Structure of a Crochet Bikini Bottom
Before diving into the row-by-row instructions, it helps to understand the anatomy of what you’re making. A crochet bikini bottom consists of three main sections.
The front panel runs from the waistband down to the crotch. It’s typically wider at the top (at the waist) and either stays the same width or narrows slightly depending on the style. A classic bikini shape stays flat and consistent. A Brazilian cut narrows more aggressively.
The gusset is the strip of fabric that runs between the legs, connecting the front panel to the back panel. It’s narrower than both panels and is the piece most people get confused by. Getting the gusset width and length right is what makes a bikini comfortable to wear.
The back panel runs from the gusset up to the waistband at the back. It’s often wider than the front at the waist and shaped with more length on the sides to give coverage over the buttocks. Full coverage styles have a taller back panel; cheeky or Brazilian styles have a shorter one.
Some patterns work all three pieces flat and seam them together. Others use a continuous method that works the front panel, transitions into the gusset, and continues into the back panel without seaming — which gives a cleaner finish. This guide will use the flat-and-seam method because it’s easier to control sizing adjustments.
How To Crochet The Front Panel
Start with a foundation chain equal to your waist measurement in stitches (use the calculation from your gauge swatch). Join to form a ring if you’re working in the round, or leave it as a flat chain if working flat.
For a flat front panel: chain your stitch count, then work single crochet across the entire row. Turn, chain 1, single crochet across again. Continue working flat until the panel reaches from your waist to the point where your inner thigh begins — approximately half of your rise measurement, minus a centimeter or two for the gusset.
Sizing adjustments for the front panel width:
If you want a high-waist style, add 1 to 1.5 inches to your starting chain and work increases at the side edges every few rows to create a flared effect. If you want a low-rise style, subtract 1 to 1.5 inches from your starting chain and work the panel as a straight rectangle.
For plus sizes (size 1X and above), the front panel often needs to be longer rather than wider, since the rise tends to be deeper on a fuller figure. Add extra rows to the front panel rather than extra stitches to the sides, and you’ll find the fit improves dramatically.
Shaping the leg openings: At approximately the halfway point of your front panel’s length, begin decreasing stitches on both sides to create the curve of the leg opening. A simple way to do this is to slip stitch over the first 3 to 5 stitches on each side, then single crochet across the remaining center stitches. Repeat this over 3 to 4 rows until you’ve reached your gusset width (typically 2 to 3 inches, or about 10 to 15 stitches). This creates the natural inward curve that shapes the leg opening.
How To Crochet The Gusset
The gusset is a simple rectangle. It should be as wide as the narrowest point of your front panel after shaping (usually 10 to 15 stitches, or 2 to 3 inches) and as long as the crotch portion of your rise measurement.
To find the gusset length, subtract the front panel length and the back panel length from your total rise measurement. Whatever remains is your gusset length. A rough guideline for most sizes is 3 to 5 inches, but this varies significantly by body type and personal preference for how the bikini sits.
Work the gusset in single crochet rows until it reaches the needed length, then leave a long yarn tail for seaming. Set this piece aside.
Many crocheters add an extra layer inside the gusset for coverage and comfort. You can do this by working a second gusset rectangle and whipstitching the two together along the edges before attaching it to the panels. This is entirely optional but recommended if you’ll be wearing the bikini as swimwear.
How To Crochet The Back Panel
The back panel is worked similarly to the front panel but is typically a bit wider and taller to provide coverage over the seat. Use your waist measurement again for the starting chain, but add 10 to 20% more stitches depending on how much coverage you want.
Work straight rows until the panel reaches from the waist to the gusset on the back side. This measurement is roughly your total rise minus your front panel length minus your gusset length.
Sizing adjustments for the back panel:
For fuller figures, the back panel benefits from a small amount of shaping through short rows. Work across to the center back, turn, and work back without completing the full row. Repeat this once or twice to add a bit of extra length in the center back, which helps the fabric lay over a fuller seat without pulling down from the waistband. This is the same concept used in pants with a seat curve and it makes an enormous difference in comfort.
For a cheeky style, reduce the height of the back panel by 30 to 40% of the standard back panel measurement. For full coverage, add a few extra rows.
Assembling The Bikini Bottom
Lay your three pieces flat and pin them together before seaming. Attach the gusset to the bottom of the front panel first, aligning the narrow edge of the gusset with the narrowest point of the shaped leg opening. Use a mattress stitch or whipstitch with your tapestry needle and a length of matching yarn.
Then attach the other narrow end of the gusset to the bottom of the back panel in the same way. Once both seams are done, fold the side edges of the front and back panels together and seam up each side, from the waist down to where the leg opening begins. Leave the curved leg opening unstitched — this creates the opening for your leg.
Turn the bikini right-side out and try it on. Check the fit at the waist, hips, gusset, and leg openings. If anything feels too tight, you can carefully open a seam and add a few rows. If it’s too loose, you can take in the side seams slightly.
Adding The Waistband and Leg Openings
Work a row of single crochet around the entire waistband edge to stabilize it. Then fold your elastic in half lengthwise and pin it to the inside of the waistband, stretching it to fit evenly as you go. Use a whipstitch to secure the elastic, working through the crochet fabric and around the elastic simultaneously.
For the leg openings, work 1 to 2 rounds of single crochet around each opening, decreasing slightly at the inner leg curve to keep the fabric flat. You can also add a round of reverse single crochet (also called crab stitch) for a neat, firm edge that looks professional.
If you want ties on the sides rather than a fixed waist, work a long chain on each side edge at the waist — about 25 to 35 chains on each side — and fold them so the chain forms a double-strand tie. Secure the end and weave in the tails. This also makes the sizing more flexible and allows the bikini to be adjusted on the body.
Finishing Touches and Care Tips
Weave in all your yarn ends thoroughly using your tapestry needle, working the tails in multiple directions to secure them. Cotton yarn can loosen up when wet, so this step is worth extra care.
Rinse the finished bikini bottom in cool water and lay it flat to dry. Do not wring it out, as this can distort the shape. Blocking the finished piece while it’s damp can help even out any uneven stitches and give you a more polished result.
When it comes to washing, rinse your crochet swimwear in cool water by hand after each use, especially after exposure to chlorine or saltwater. Both will degrade the fibers over time. Lay flat to dry rather than hanging, since cotton gets heavy when wet and can stretch under its own weight.
Adjusting The Pattern For Any Size
Here is a quick summary of the key adjustments that allow this pattern to work for every body:
For smaller sizes (XS to S), reduce your starting chain to match your waist measurement and work fewer rows in the gusset. The front and back panels will be shorter overall.
For medium sizes (M to L), follow the base pattern as written using your own measurements.
For larger sizes (XL to 2X), increase the back panel height and add short-row shaping over the seat. Consider adding a few extra stitches to the side seams before closing them, and check that the leg openings aren’t too snug.
For plus and extended sizes (3X and beyond), the rise measurement becomes the most important number. Add length to both panels and to the gusset, and use the short-row shaping method in the back panel as a standard feature rather than an optional one.
The beauty of crochet is that it’s infinitely adjustable. No two bodies are alike, and this pattern is built around your measurements rather than a generic sizing chart.
Final Thoughts
Learning how to crochet a bikini bottom the right way takes a little patience with the measuring and fitting process, but once you’ve made your first one, the second will come together in a fraction of the time. The key takeaways are to always swatch, always measure your own body rather than relying on size labels, and to embrace the adjustability that crochet naturally offers.
Your handmade crochet bikini bottom will be more durable, more flattering, and far more unique than anything you’d find in a store. Whether you keep it simple in a classic solid or experiment with colorwork, shells, or surface crochet details, you’re creating something entirely your own — and that’s what makes this craft so worthwhile.
