A rash guard is a close-fitting athletic shirt made from nylon or polyester blended with spandex, worn in and out of the water for sun protection, warmth, and abrasion resistance. The name comes from surfing, where the shirt prevents the chafing and rash caused by a wax-coated board against bare skin. Today rash guards cover a wider range of use: swim training, open water, snorkeling, paddle sports, and everyday UV protection at the pool and beach.
UPF 50+ Sun Protection
Most rash guards carry a UPF 50+ rating, which blocks 98 percent of UVA and UVB rays. Unlike sunscreen, the fabric does not wash off or need reapplying, so a rash guard is the standard pick for long sun exposure, kids at the pool, and anyone with sensitive skin. The tight knit and synthetic fiber hold the UPF rating through repeated wear and wash cycles.
Sleeve Length and Cut
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Long-Sleeve: Maximum arm and torso coverage, the standard pick for full sun protection, surf, and cooler water.
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Short-Sleeve: Shoulder and core coverage with more arm mobility, the option for warm-water swim and high-output paddle sports.
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Zip-Front: Front-zip entry that is easier to put on and take off when wet, common in Xcel and O'Neill surf-cut styles.
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Compressive vs Relaxed Fit: Compression cuts sit close to the skin for drag reduction and layering under a wetsuit; relaxed cuts wear loose over a swimsuit for casual coverage.
Rash Guards for Swimming
For lap swim, open water, and pool training, a fitted rash guard adds sun and warmth coverage without restricting stroke mechanics. Chlorine-resistant polyester construction holds up to repeated pool use better than cotton or standard blends, and a flatlock-seam build reduces chafing during repetitive arm movement. This swim-specific use is where the SwimOutlet catalog runs deepest, alongside surf and beach cuts.
Fabric and Construction
Rash guards use a nylon-spandex or polyester-spandex blend for stretch and quick drying. Flatlock seams lay flat against the skin to prevent rubbing, and a higher spandex percentage gives a more compressive fit. For chlorinated pools, polyester-dominant blends from Sporti and TYR last longer than nylon-dominant surf fabrics.
Rash Guard vs Swim Shirt vs Sun Shirt
The terms overlap, with small differences. A rash guard is the fitted, stretch athletic top built for surf and swim. A swim shirt is often looser and worn more for casual sun coverage than performance. A sun shirt or sun shirt UPF top prioritizes the UV rating and may use a lighter, looser weave. All three protect skin from UV rays; the choice comes down to fit and activity, with fitted rash guards preferred for active swim and surf, looser swim shirts for relaxed beach and pool wear.
Shop Rash Guards by Wearer
Rash guards run across every age and fit. For men's cuts, see men's rash guards and swim shirts. For women's cuts, see women's rash guards and swim shirts. For kids, see girls' rash guards and sun protection and boys' rash guards and sun protection. For help choosing a fit and fabric, see the rash guard buying guide.
