5 cm Bikini Bottom Fit: How to Choose Your Swim Brief Size
By Marlies Dekkers Lingerie & Swimwear | Published: 2026-11-03
Category: Buying Guides
Use side width, coverage, and fabric clues to choose a 5 cm bikini bottom that fits. A practical sizing guide for buying swim briefs online.
Quick answer
Choose a 5 cm bikini bottom by your hip measurement first, then use the 5 cm side width as a coverage signal: it sits between a skimpy string and a fuller brief. If you are between sizes or want a stay-put fit, size up rather than down.
What 5 cm side width actually means for coverage
Side width is the height of fabric at the hip, not the amount of back coverage. A 5 cm side gives a mid-rise, moderate look that covers the hips and buttocks without the narrow feel of a 4 cm thong or the fuller seat of a high-waist brief. It is a good middle ground if you want a swim brief that feels secure but still shows shape.
Because the side width is fixed, the variable that changes most between sizes is how the fabric sits around your hips and seat. If the side band digs in, the brief will ride up when you swim; if it gapes, the back will not stay put.
Why fabric finish matters when you size online
Two swim briefs can share the same 5 cm side and fit differently because of the fabric. Matte and glossy fabrics can behave differently in water: a glossy surface may feel slicker against the skin, while a matte finish can feel more stable. Ton sur ton styling, where two tones of the same color meet, also changes how the edges read on the body, so the same cut can look more or less revealing depending on the finish.
When you cannot try a brief on, read the product description for fabric finish and any shaping details. A formfitting cut with a shaped back will feel different from a flat-cut brief even at the same side width.
The trade-off: coverage versus adjustability
A fixed 5 cm side gives a clean, predictable silhouette, but it offers less adjustability than tie-side or fold-down styles. If you often fall between sizes, or your hip measurement changes, a fixed-side brief leaves less room to tweak the fit. The upside is that there is no tie to come loose and no folded waistband to bulk up under swimwear.
Choose a fixed 5 cm side when you want a set-and-forget fit. Choose an adjustable style when you want to fine-tune coverage for different beaches or activities.
Decision rules for choosing your 5 cm bikini bottom size
- Start with hip measurement: Measure around the fullest part of your hips and seat, keeping the tape level. Compare that number to the size chart, not your usual clothing size, because swimwear sizing can differ from ready-to-wear. If your hips fall between two sizes, choose the larger size for a 5 cm fixed side.
- Use side width as a coverage filter: If you want more coverage than a 4 cm thong but less than a high-waist brief, a 5 cm side is the right middle ground. If you prefer minimal coverage, look for a narrower side; if you want fuller coverage, choose a wider side or a high-waist cut.
- Check the back construction: Look for a shaped back or pleating details that frame the seat, as these can affect how the brief sits. A flat-cut back may feel different from a shaped one at the same side width. Read the description for back coverage language before you buy.
- Match fabric to your activity: For swimming laps or active beach days, choose a brief with a stable, matte finish and a snug hip band. For lounging or sunbathing, a glossy finish is fine as long as the size is correct.
- Plan for how it feels in water: A 5 cm brief should stay put when wet. If you are between sizes and plan to swim, size up so the band does not dig in and cause riding up. Test the fit with a gentle stretch at the hip before removing tags.
Product facts that help you choose
- 5 cm bikini bottom: 5 cm sides with a formfitting shape designed to suit all body types. The 5 cm side is the key coverage marker: it gives moderate hip coverage without the narrow feel of a thong, so use your hip measurement to pick the size.
5 cm bikini bottom - 5 cm bikini bottom: Sea green ton sur ton fabrics, one matte and one glossy, with a gold-metal ornament at the back. The mixed finishes and back ornament add visual interest, but they do not change the fit, so base your size on measurements rather than the styling.
Who a 5 cm bikini bottom suits
Best for
- Swimmers who want moderate hip coverage without a high waist
- Buyers who prefer a fixed side over tie-side adjustability
- Anyone looking for a mid-rise brief that frames the seat
Not for
- Shoppers who want minimal string-bikini coverage
- Those who need to adjust coverage throughout the day
- Buyers who prefer a high-waist or tummy-control cut
