Baby Swimwear Buying Guide: Nappies, Fit and Sun Protection

Quick answer

For most babies, choose a snug but not tight one-piece or two-piece swimsuit with a high UPF rating, and pair it with a well-fitted reusable or disposable swim nappy. Prioritise a secure leg and neckline over room to grow, because loose fabric floats up and chafes. If your baby is between sizes, size down for water safety and up only if the next size still passes the two-finger test at the leg.

Why baby swimwear is different from everyday clothing

In water, fabric behaves differently: it gets heavier, clings and can pull a swimsuit away from the body. A baby swimsuit needs to stay in place during kicking, floating and being lifted in and out of pools. That means the fit should be closer than a t-shirt or leggings, with enough stretch to move but not so much room that the suit balloons. Look for flat seams and soft bindings around the neck and legs, because these are the areas that rub when wet.

Swim nappies: reusable versus disposable

A swim nappy is not a regular nappy. It is designed to contain solids and slow down leaks, not absorb pool water. Reusable swim nappies have a snug waist and leg seal and can be washed and reused, which suits frequent swimming. Disposable swim nappies are convenient for travel or occasional dips but must be changed as soon as you leave the water. Many swimsuits now include an integrated swim nappy, but if yours does not, you will need a separate one underneath. Always check the leg and waist fit of the nappy before the swimsuit goes on.

Fit guidance: how to check a baby swimsuit

Start with the leg openings. You should be able to slide one finger comfortably under the leg elastic, but not two. If you can fit two fingers, the suit is too loose and may gap in the water. Next, check the neckline: it should sit flat against the chest without digging in. Lift your baby's arms overhead; the suit should not ride up over the chin. For two-piece suits, the top should overlap the bottom by at least a few centimetres so there is no gap when your baby bends or floats. If the suit leaves red marks or your baby fusses when you put it on, size up only if the larger size still passes the leg check.

Sun protection: what UPF means for baby swimwear

UPF (Ultraviolet Protection Factor) indicates how much UV radiation passes through fabric. A UPF 50+ rating blocks the vast majority of UV, but it is not a substitute for shade, a hat and sunscreen on exposed skin. For babies under six months, keep them out of direct sun and use shade and protective clothing rather than relying on sunscreen. When choosing swimwear, look for high necklines, long sleeves or legs if you want more coverage, and darker or denser fabrics if you want extra reassurance. Remember that stretched or wet fabric can offer less protection, so a snug fit also helps here.

Fabric and care for baby swimwear

Most baby swimwear is made from a chlorine-resistant blend of polyester and elastane, which holds its shape better than cotton in pools. Rinse swimwear in cool fresh water immediately after swimming to remove chlorine and salt, then hand wash or use a gentle cycle and air dry away from direct heat. Avoid fabric softener, which can coat the fibres and reduce stretch. If the suit starts to sag or the elastic feels loose, it is time to replace it, because a stretched suit will not stay in place.

What to pack for a baby swim session

Beyond the swimsuit and nappy, bring a hooded towel, a wet bag for the used suit, a hat with a brim, and a change of clothes. A reusable swim nappy needs a spare in case of a change. If you are swimming outdoors, a terry towelling hat like the Surfs Up Terry Beach Hat can be a practical choice for older babies and toddlers, but for babies under one, prioritise a soft, secure sun hat that stays on. Always check the pool's nappy policy: some require a specific type of swim nappy under swimwear.

Decision rules for buying baby swimwear

• Rule 1: Fit first, size second: Always prioritise a snug fit over room to grow. A swimsuit that gaps at the leg or neck will leak and chafe. Use the one-finger leg test and check the neckline lies flat. If in doubt, size down rather than up.
• Rule 2: Match the nappy to the swimsuit: If your swimsuit has no integrated nappy, choose a reusable or disposable swim nappy that fits snugly under it. Reusable suits frequent swimmers; disposable suits travel and occasional dips. Check the pool's nappy rules before you buy.
• Rule 3: UPF is a starting point, not a shield: Choose high UPF fabric, but combine it with shade, a hat and sunscreen on exposed skin. For babies under six months, avoid direct sun entirely. Coverage and shade matter more than any single UPF number.
• Rule 4: Rinse and air dry every time: Chlorine and salt break down stretch fibres. Rinse in cool water after every swim and air dry away from radiators. Skip fabric softener. Good care keeps the fit secure for longer.

Product facts

• Surfs Up Terry Beach Hat: Surfs Up Terry Beach Hat is made from soft, 100% cotton terry towelling with a curvy wave pattern of red, golden yellow, melon pink and blue, and has a wide brim. A wide brim helps shade the face and neck during outdoor water play, and the terry towelling is absorbent for post-swim hair.
• Limoncello Stripe Organic Cotton European Pillowcases: Limoncello Stripe Organic Cotton European Pillowcases are made from 100% GOTS certified organic cotton and feature a lemon yellow and white stripe. While not swimwear, this shows the brand's use of certified organic cotton, which some parents prefer for sensitive skin; however, for swimwear, look for chlorine-resistant synthetic blends as noted in the fabric section.

Who this guide is for

Best for

• Parents buying a first swimsuit for a baby aged 0–24 months
• Caregivers who want a swimsuit that works with reusable swim nappies
• Families who swim regularly and need durable, well-fitting swimwear

Not for

• Older children or adults who need standard sizing and styles
• Buyers looking for fashion-only swimwear without sun protection or nappy compatibility
• Those who prefer loose, roomy clothing for water play