UV Protection Factor or "UPF" The Ultraviolet Protection Factor
(UPF) rating system measures the UV protection provided by
fabric. It is very similar to the SPF rating system used for
sunscreens. A garment with a UPF of 50 only allows 1/50th of the
UV radiation falling on the surface of the garment to pass
through it. In other words, it blocks 49/50ths or 98% of the UV
radiation. All Coolibar brand garments rate UPF 50+, which is
the highest possible rating. To request a Coolibar catalog,
click here. Coolibar uses independent laboratories for our sun
protective clothing tests. We conduct an initial UV
transmittance test, then launder the garment 40 times, expose it
to 100 fading units of simulated sunlight, then conduct a second
UV transmittance test. The tests measure transmittance across
both the UVA and UVB spectrum. Garment ratings are based on the
lower result of the initial "brand new" test and the second
"life cycle" test. Most fabrics lose some level of UV protection
as they age, so most fabrics are r