Swimwear: Fit, Lining and Care

A swimsuit is built from elastic fabric, worn stretched, then exposed to everything that attacks elastic. That explains nearly all of its behavior: why it fits differently wet and dry, why a suit that fit in the store feels loose by season’s end, and why care matters more here than for almost any other clothing.

Separate the structural questions from the seasonal ones. A suit that lost its shape because the elastane aged is different from one that never fit, but they get confused because the symptom (a suit that doesn’t hold) looks the same.

What water and sun do to fabric

The elastic fiber, usually elastane, is what lets the fabric stretch and return. Chlorine, in most treated pools, degrades it over time. Salt water does less damage but leaves residue that holds grit in the weave. Heat, from a hot tub or a hot wash, speeds up all of it.

Sunscreen is its own problem. Oils and mineral particles can mark the fabric, affect the fiber surface and permanently stain a pale lining. It’s worse when you put the suit on right after applying, so let sunscreen dry first.

Sun itself breaks down elastic over long exposure, one reason a suit dried in direct sun ages faster than one dried in shade.

Lining and the second layer

Swimwear lining isn’t decorative. A double layer across front and seat adds structure, keeps wet fabric opaque and spreads the stretch over more material.

Front lining does the most for support, because two layers resist stretching more than one. An inner shelf in the bust is a simpler version; a molded cup is a third. Which you want depends on how much support you need and how the outer fabric behaves wet.

Wet fabric is heavier, less opaque and stretchier than dry. That’s why a suit that looks fine in the store feels different after a lap: the outer layer relaxes and your body moves differently.

A suit with a single front layer and no internal support changes most when wet. That’s a manufacturing choice, worth checking before buying, not after.

Sizing: read the swim chart, not your dress size

Swim charts are often their own thing. Torrid’s wireless one-piece chart, for example, runs from size 00 (bust 38–40 in, hip 42–44 in) to size 6 (bust 66–70 in, hip 72–76 in), and its size 2 covers a 46–50 in (117–127 cm) bust and 50–54 in (127–137 cm) hip (per torrid.com, Oct 2026). Those are 4 in bands, wide enough that where you fall inside one matters. If you’re at the top of the bust band and the bottom of the hip band, look for separates or a suit with adjustable straps.

Straps, back and gusset

Three areas decide whether a suit stays put.

Straps. They should lie flat without cutting in and stay on your shoulders when you move. Pick adjustable ones when you can, so you can shorten them as the suit relaxes. Thin straps concentrate the load; wider straps or a cross-back spread it.

The back. A racerback, with straps meeting between the shoulder blades, holds the shoulders without making them carry the load. A low back relies on the straps and the body of the fabric and moves more when you swim. Neither is better in the abstract; they fail differently.

The gusset (the crotch) should lie flat, with leg openings neither cutting in nor standing away. A lined gusset is normal. If it pulls to one side when you stand, the leg openings or body length are wrong for your torso, and no adjustment fixes that.

The body needs enough length for you to stand upright without the straps lifting the whole suit. If it rides up when you stand straight, it’s short in the torso.

The moves to test

Work through the same sequence you’d use for any close-fitting piece:

• Stand and raise both arms; straps stay on, gusset doesn’t lift.
• Reach forward and down toward your toes; does the back pull away from you?
• Twist and bend side to side; leg openings stay in place.
• Sit and cross your legs; gusset and side seams shouldn’t dig.
• If you can do it safely, get the suit wet in a shower before deciding. Wet fit is the fit that matters.

Test with the sunscreen you’ll actually use, since it changes the friction between skin and fabric.

Rinsing and drying

Rinse in cool fresh water as soon as you reasonably can, ideally while it’s still wet. That clears chlorine, salt, sunscreen and grit before they settle into the weave. A short soak in cool water, a tiny bit of mild soap to lift oils, then a thorough rinse is plenty.

Don’t wring it. Wringing twists the fabric and pulls the elastic, and doing it repeatedly stretches the suit for good. Press water out between flat hands, or roll it in a towel and press.

Dry flat, in shade, away from heat. Don’t hang a wet suit by its straps; the water weight stretches them. No plastic bags, no hot cars, no dryer. Heat is the main thing that ages elastane.

When a suit is truly done

A suit that’s lost its stretch feels soft and doesn’t snap back when you pull it. That’s fiber fatigue, and it can’t be undone. A suit that still springs back but no longer fits is a different issue, usually a change in your body, not a failure of the suit.

Simple test: stretch a bit of fabric at the leg opening or strap and let go. A healthy suit returns fast and firm. One that returns slowly or not at all is finished for swimming, though it might still work as a layer.

If the elastic’s gone everywhere, the failure’s uniform. If it’s failed in one spot, like a strap or seam, that’s usually a repair, not a replacement.

Care that gets you the most seasons

• Rinse after every wear. No exceptions.
• Hand wash in cool water with mild soap; if you must machine wash, use a mesh bag on cold delicate.
• Never wring, bleach or use fabric softener, which leaves a film that stops the fabric shedding water.
• Dry flat in shade, never on a radiator or in a dryer.
• If you swim often, rotate two suits so each gets time to recover.
• Put sunscreen on before dressing and let it dry.

A suit treated like this holds its shape for several seasons of regular swimming. One that isn’t can lose its recovery in a single summer, and the difference is almost all routine, not the suit.