To the untrained eye, a bikini is simply two small pieces of fabric held together by string. However, in the world of fashion design and garment manufacturing, the bikini is a masterpiece of precision engineering. Because swimwear must withstand movement, water weight, and harsh chemicals—all while covering very little surface area—every component must serve a specific purpose.
Whether you are an aspiring designer creating your first Tech Pack or a shopper trying to find the perfect fit, understanding the anatomy of a bikini is essential. In this guide, we will break down every part of the bikini top and bottom, from the visible hardware to the hidden internal structures.
The bikini top is the most complex half of the set. Its primary goal is to provide aesthetic appeal while offering varying levels of support and coverage.
The triangle top is the classic two-triangle shape with ties at the neck and back (or sometimes fixed straps). It’s simple, adjustable, and instantly reads as “bikini,” which is why it shows up in almost every collection.
A halter top ties or fastens around the neck and usually closes at the back with ties or a clasp. Visually it gives a lifted, centered look, and it tends to feel more “locked in” than a triangle.
A bandeau is a straight, strapless band across the chest, sometimes with a twist front or center ring detail. It’s popular for tanning and minimalist styling, and it looks clean in solid colors and simple prints.
An underwire bikini top uses a wire channel under each cup to create a lifted, bra-like shape. It’s one of the best options for structured support and a more defined silhouette, especially for fuller busts.
A micro bikini top is an ultra-minimal version of the triangle top, using very small cups and thin ties or straps. It’s designed for maximum tanning and a bold, fashion-forward look, so it usually fits best in capsule drops, influencer styles, or tanning-focused collections rather than “everyday” swim lines.
A plunge top has a deep V center front, creating a lower neckline and a more dramatic shape. It’s a strong fashion silhouette and works well when you want a sexy look without going minimal on coverage everywhere.
A long sleeve bikini top is built like a cropped rashguard or surf top, with full-length sleeves and a fitted body. It’s popular in active swim and resort collections because it looks modern, offers more sun coverage, and pairs well with both high-waist bottoms and sporty briefs.
Sport bikini tops use higher necklines, wider straps, and sometimes a racerback. They’re designed for activity, so they look athletic and feel secure for swimming, beach sports, or surfing-style collections.
One-shoulder tops use a single strap for a fashion-forward, asymmetric look. They photograph well and can make a collection feel more trend-driven without changing fabrics or prints.
Wrap or cross-front tops create overlapping panels or straps that cross at the front (and sometimes wrap around the body). They give a flattering shape and can feel adjustable, which customers like.
A tankini is a two-piece style where the top is longer, usually covering the midriff like a fitted tank. It sits between a bikini and a one-piece in terms of coverage, so it’s popular for resort, family, and “more comfortable but still cute” customers.
The Cups: The cups are the shaped pieces that cover the bust and create the top’s silhouette. In swimwear they can be made with seamed fabric panels, foam, molded cups, or a simple lined “soft cup” construction depending on how much structure you want.
The Apex: is the “peak” of the bikini cup where the fabric transitions into the shoulder strap. In manufacturing, this is a high-stress point. If the apex is not reinforced with extra “bar-tack” stitching, the strap is likely to snap during vigorous activity like swimming or beach volleyball.
The Bridge
The bridge is the center connector between the two cups.
Wings and Side Panels: The wings are the parts of the bikini top that wrap around the ribcage toward the back. In “tie-back” styles, these transition into strings; in “clasp-back” styles, they are wider panels designed to provide support and prevent the top from sliding down.
Underwire : Underwire is the curved wire inserted under the cup inside a wire channel. Its job is to lift, separate, and support the bust by giving the cup a rigid base.
Side Boning: Often hidden inside the side seams of strapless or bandeau tops, boning consists of small, flexible plastic inserts. These “stays” prevent the fabric from bunching up or rolling down, ensuring the bikini maintains its vertical height against the body.
Bikini bottoms are defined by their “rise” (where they sit on the waist) and their “coverage” (how much they show in the back).
High-waist bottoms sit at or near the natural waist, offering more belly coverage and a vintage-inspired shape. They’re popular across many markets because they feel secure, flatter the midsection, and pair well with everything from triangle tops to bandeaus.
Tie-side bottoms use adjustable side ties, usually in a triangle or minimal coverage shape. They’re popular for tanning and vacation styles because they’re adjustable and have a playful look.
Cheeky bottoms are cut to show more of the lower cheek while still keeping a wider back panel than Brazilian or tanga. They’re a strong “fashion core” style because they photograph well and feel sexy without going extreme.
Brazilian cuts reduce back coverage more than cheeky and usually have a curved or V-shaped back seam that visually lifts the glute. It’s a popular choice for brands that want a trend-forward look while still feeling more substantial than a thong.
Thong styles have very minimal back coverage, with a narrow back strip or string. They’re common in tanning-focused drops and bold fashion capsules where the goal is the least tan line and the most revealing silhouette.
V-cut or high-leg bottoms use a higher leg opening and angled front that visually lengthens the legs. Coverage can range from cheeky to moderate, but the key feature is the leg line sitting higher on the hip.
A skirted bottom adds a small skirt layer over a bikini bottom base, giving extra coverage around the hips and upper thigh. It’s a strong option for modest collections and resort customers who want comfort without switching to a one-piece.
Boyshorts add more leg coverage and a fuller back, creating a sporty, secure silhouette. They work well for active swim, surf-inspired looks, and customers who prioritize comfort and coverage.
Unlike a standard pair of briefs, bikini panels are often cut with “Negative Ease.” This means the fabric is intentionally cut smaller than the body it is meant to cover, relying on the fabric’s “modulus” (stretch power) to hold it in place.
The gusset is the narrowest part of the bottom that sits between the legs.
These are the “apertures” of the garment. In most bikinis, these edges are reinforced with swim-grade elastic (usually rubber or Framilon) to ensure the suit stays in place when hit by a wave.
Many modern bikini bottoms feature a “Ruched” or “Scrunched” back seam. This involves sewing a piece of elastic into the center back seam while it is stretched. When released, it gathers the fabric, creating a “heart shape” that accentuates the curves of the glutes.
What makes a bikini “high-quality” is often what you cannot see from the outside.
Most bikinis are “self-lined” or “contrast-lined.”
Not all elastic is created equal. Standard rubber bands will disintegrate in months.
Many bikini tops include small “pockets” in the lining. The pads (sometimes called “cookies”) provide extra coverage and shape. They are usually made of closed-cell foam that doesn’t absorb water.
Hardware refers to the functional and decorative metal or plastic pieces used to join the garment together.
| Part Name | Function |
| Rings | Connects the straps to the cups; allows for multi-way strap configurations. |
| Sliders | Allows the user to adjust the length of the straps (like a bra). |
| G-Hooks / Clasps | The closure mechanism at the back of the top. |
| Cord Ends (Aglets) | Decorative weights at the end of strings to prevent fraying and add a premium feel. |
You cannot build a bikini with a standard straight stitch. Because the fabric must stretch, the thread must stretch too.
If you are a designer, failing to specify the diameter of a ring or the GSM of the lining in your tech pack can lead to a production run that is either “see-through” or “fits too small.”
Understanding parts like the Apex height or Gusset width allows you to design for specific body types. For example, a “curvy” line might require a wider under-bust band and reinforced wings to provide the necessary support without sacrificing style.
Luxury is found in the hardware. Using Gold-Plated Zinc Alloy instead of plastic sliders immediately elevates a $20 bikini to a $150 designer piece.
The shell is the outer fabric you see (your color/print and texture). The lining is the inner layer that improves coverage, comfort, and stability.
A cup pocket is an inner layer with an opening so the wearer can insert or remove pads. Fixed cups are sewn in (or lightly bonded) and stay in place. Cup pockets offer flexibility, while fixed cups give a cleaner look and more consistent shaping.
Wider straps and stable strap attachment points generally improve support. Adjustable straps help fit more body types.
A bikini is far more than a fashion statement; it is a complex assembly of specialized fabrics, chemical-resistant hardware, and high-tension engineering. By understanding the anatomy of a bikini—from the Apex of the top to the Gusset of the bottom—you gain a deeper appreciation for the craftsmanship required to create “the perfect suit.”
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