“UPF” stands for Ultraviolet Protection Factor and it measures the Ultraviolet radiation or “UV” protection from the sun provided by a fabric. (Similar to the SPF rating system used for sunscreens.)
Our Swimsuits For All styles with UV sun protection have a rating of UPF 50 (the highest possible rating) which means only 1/50th of the sun’s UV rays can pass through, and it blocks 98% of UV rays. Sunscreen use is still recommended when wearing our UPF 50 styles since no clothing can completely block out UV rays.
Please note that most fabrics lose some of their UV protection over time from repeated washing and wearing. Garments that are damp or wet typically provide less UV protection (this is especially true of lighter fabric colors). Also, on any UPF 50 suit that had mesh or other fabric panels, those panels would not provide the same UPF 50 protection.