What UPF 50+ Actually Means, and Why It Belongs on Your Swimwear Checklist

For years, swimwear shopping came down to two questions: does it fit, and do I love it? Lately, a third question has moved up the list, right alongside them: is it protecting my skin?

Searches for UPF 50+ and sun-protective swimwear have been climbing steadily, and it's not hard to see why. Women who've spent years investing in sunscreen, hats, and skincare routines are starting to ask why their swimsuit isn't held to the same standard. It's a fair question, and one worth understanding properly before your next purchase.

What UPF actually measures

UPF stands for Ultraviolet Protection Factor. It's a rating applied to fabric, not skin, and it tells you how much UV radiation gets through the material to reach you.

A fabric rated UPF 50+ blocks the vast majority of UV rays, letting through only a small fraction. For comparison, a plain white cotton shirt, the thing most people assume is "covering up," offers surprisingly little protection once it's wet.

That is differ from SPF, which is a skincare measurement for sunscreen. UPF is about what your clothing is doing for you while the sunscreen underneath wears down over the course of a day at the beach or pool.

Why swimwear needs to catch up

Swimwear has always been treated a little differently than the rest of a wardrobe. It's cut for movement and shape, not coverage, so sun protection was rarely part of the design conversation.

But swimwear is arguably the piece of clothing your skin spends the most consecutive hours in direct sun. A tighter weave, a denser knit, and the right fibre blend all affect how much UV actually reaches your skin, not just how the fabric looks or drapes. That's why we build every SUZU swimwear piece on premium, densely constructed fabric first.

This is why fabric choice matters so much. Sheer, thin, loosely knit fabrics let more light through, regardless of sun protection. Fabric that's been engineered for structure and density, the kind that holds its shape after hours of wear and repeated swims, naturally tends to offer better coverage against UV as well.

What to actually look for when you're shopping

Sun protection in swimwear isn't only about a UPF number on a tag. A few things to check:

• Fabric density and weave. Tighter weaves and thicker knits generally block more UV than sheer or loosely constructed fabric.
• Coverage of the cut itself. A high-cut leg or plunging neckline is a style choice, not a protection strategy. If sun exposure is your priority, factor coverage into your silhouette choice, not just which one is trending. Our one-piece swimsuits and high-waisted bikini bottoms are a good place to start if fuller coverage is the priority.
• How the fabric performs when wet. Some fabrics lose structure and protection once soaked. Quick-drying, four-way stretch fabric tends to hold its integrity better across a full day in and out of the water.
• Construction quality. Double-lined pieces, in particular, tend to offer more consistent coverage than single-layer fabric, simply because there's more material between you and the sun.

Where this fits into how we think about design

At SUZU, our pieces, like the HOLLY One-Piece and the CHLOE Collection, are built from premium, densely constructed swim fabric with four-way stretch and double-lined construction. The same qualities that support structure, longevity, and shape retention also contribute to how much coverage a fabric naturally offers against the sun. It's part of why we hold fabric quality to the standard we do, not as a separate feature, but as one more reason quality construction matters.

We'll be exploring UPF-specific styles and features more closely in future collections, because it's clearly where our community's priorities are heading, and it's a natural extension of what we already care about: swimwear built to be worn, not just looked at.

Sun protection is part of good design now

Sun protection shouldn't be an afterthought to how a swimsuit looks. As more women start asking about UPF ratings and fabric performance, the swimwear industry is being pushed to treat protection as part of good design, not a separate category. That shift is a good one.

Looking for swimwear built on real fabric quality, not just trend? Explore the current SUZU swimwear collection.

Frequently Asked Questions