The Ultraviolet Protection Factor (or “UPF”) rating measures the UV protection provided by a fabric. It is similar to the SPF rating system used for sunscreens.

Lands’ End® swimwear’s rating is UPF 50, which is the highest possible rating. That means it only allows 1/50th of the UV radiation to pass through it — blocking 98% of harmful rays. However, no clothing can completely block out UV rays so the use of sunscreen is still recommended.

Note: there are several factors that may affect the level of UV protection. Most fabrics lose some of their UV protection if the garment is stretched out or worn, or if it has been washed repeatedly. Also, when the garment is damp or wet, the amount of UV protection is typically reduced. Lighter colors also tend to lose more of their sun protection when damp or wet than darker colors.