Girls' Swimsuits & Swimwear

Girls' swimsuit sizing typically follows standard clothing sizes: 2T–5T for toddlers, 4–6X for little girls, 7–16 for big girls and teens. However, sizing varies significantly between brands — a Speedo size 8 may fit differently than a Billabong size 8. We recommend measuring your child's chest, waist, and hip measurements and comparing them to the brand-specific size chart on each product page. If your child is between sizes, size up for comfort — swimwear stretches when wet, and a slightly larger suit won't restrict movement during swimming. For competitive swim team suits, size down for a compression fit that reduces drag.

For girls who swim multiple times a week — whether for swim team practice, swim lessons, or just regular pool time — choose chlorine-resistant polyester-blend fabrics. Look for labels like Speedo Endurance+, TYR Durafast Elite, or Arena MaxLife. These fabrics last 5–10 times longer than standard nylon-spandex in chlorinated water. Standard nylon-spandex blends are perfectly fine for occasional beach and vacation use and tend to feel softer. Always rinse the swimsuit in cool fresh water after every swim session and avoid putting it in the dryer — heat breaks down elasticity faster than chlorine does.

Tween girls (roughly ages 8–12) are transitioning between kids' and teen styles, so finding age-appropriate swimwear that they actually want to wear can be tricky. Popular tween swimsuit styles include tankini sets (full coverage with trendy prints), high-neck one pieces with sporty cutouts, and two piece sets with longer crop-top style tops. Rash guard sets are another great option — they provide UPF 50+ sun protection and generous coverage while still looking cool. Avoid adult-styled bikini cuts for younger tweens; instead look for tween-specific lines from brands like Billabong, O'Neill, and Seafolly that design age-appropriate styles with current trends.

Many girls' swimsuits — especially rash guards, swim shirts, and full-coverage one pieces — are rated UPF 50+, which blocks over 98% of the sun's UV rays. UPF (Ultraviolet Protection Factor) is the fabric equivalent of SPF for sunscreen. Darker colors and tighter weaves naturally offer more UV protection. For extended outdoor swimming, pair a UPF-rated rash guard top with swim shorts or a swim bottom for maximum coverage. Even with UPF-rated swimwear, apply waterproof sunscreen to exposed skin, especially the face, neck, and backs of hands. All of our girls' rash guards are rated UPF 50+.

SwimOutlet stocks girls' swimwear from a wide range of brands across competitive, active, and fashion categories. For swim team and training: Speedo, TYR, Arena, Nike, and Dolfin. For beach and fashion: Billabong, O'Neill, Roxy, Seafolly, and Hobie. For value and everyday swimming: Sporti (our house brand), Kanu Surf, and Malibu Dream Girl. We carry toddler through teen sizes across all brands, with many styles available in extended and plus sizes. Every swimsuit comes with our price match guarantee and free shipping on orders over $49.

Both styles have advantages depending on age, activity, and preference. One piece swimsuits are best for swim team, swim lessons, water parks, and active water play — they stay securely in place during diving, flipping, and sliding. Two piece sets (bikinis and tankinis) are easier for bathroom breaks — a major consideration for younger kids and for long pool days. Tankinis offer the coverage of a one piece with the convenience of a two piece. For competitive swimming, one piece athletic suits are standard. For beach and casual pool use, let your daughter choose the style she feels most comfortable and confident wearing.