You’re probably aware how damaging the sun’s rays can be—that’s why sunscreen is on every packing list for every outdoor trip ever. It’s why we often wear sun hats and sun shirts outdoors. But did you know that different materials—even different colored fabrics—offer different amounts of protection from the sun’s damaging rays? Here we explain what all those sun-related acronyms mean—UV, UPF, SPF—and how to choose the best protection.

What is UPF?

“UPF is the textile rating system that rates the amount of ultraviolet radiation blocked by the fabric,” says Sr. Product Manager Kylene Wolfe. UPF stands for Ultraviolet Protection Factor, and it’s used to rate apparel—it’s not applied directly to the skin.

How is UPF different from SPF?

UPF applies to textiles, while SPF—or sun protection factor—applies to sunscreen. “SPF is a sunscreen rating regulated by the Food and Drug Administration,” Kylene says. “SPF products are applied directly to the skin.”
SPF numbers most commonly apply only to UVB rays, which affect the outer layer of the skin and are responsible for sunburns and some surface-level skin cancers.
UPF-rated fabrics, on the other hand, block both UVB rays and UVA rays, which can penetrate into the lower levels of the skin.

What are the benefits of UPF clothing?

While sunscreen requires even application and must be reapplied, UPF-rated clothing provides consistent, even coverage and is easy to put on. Once you put on UPF-rated clothing, you’re protected until you take it off. No need to reapply.
Sunscreen can also expire, whereas UPF protection lasts the lifetime of the garment, Kylene says. UPF-rated clothing and accessories also provide protection without greasy or fragrant lotions.
Another perk of UPF-rated clothing is that it works whether it’s dry or wet. No need to worry about washing off your protection when you get sweaty on the trail or raft through splashy rapids.


What does the UPF number mean?

The higher the UPF rating, the greater the protection it offers. For example, UPF 50 allows only 1/50th of the sun’s UV radiation to reach the skin.
“There are three categories for labeling UPF garments,” Kylene says. Good is 15-24%, Very Good is 25-39%, and Excellent is 40-50+%.

What makes one product have a higher UPF rating than another?

“Fabric construction, fibers, weave, density and color all affect the UPF rating of garments,” Kylene says. “For example, cotton feels comfortable in summer heat, but untreated, it ranks last in UV protection, whereas polyester, nylon and other synthetic fibers often have a chemical structure that boosts their sun protection.”

That’s why Outdoor Research uses more technical synthetic fibers in our sun line. “We try not to add chemicals (UV absorbers & blockers) to improve the UPF rating,” Kylene says.

Also, dark colors use more dye so they absorb more UV radiation and provide better protection, Kylene says. “Dark colors don’t reflect the light back out—they absorb more light/energy from the sun. Light colors, like white, reflect the light back towards the body which equals less protection.”

But it’s important to note that the ratings that we claim are based on the lightest color of a particular item because we do not add chemicals to our fabrics, Kylene says. “We rate a product with the lowest rating from the lightest color offered. So some colors of a style could have a higher UPF rating, but we call out a lower rating due to a lighter color in the style. It’s rated per style.”

Is there a certification for UPF-rated products?

Fabric mills have their own testing and send us their reports, Kylene says. “UPF testing is voluntary for apparel, but if you claim it, you have to be able to prove it with test reports. Also, no clothing item with a UPF of less than 15 can be labeled as ‘sun-protective.”

Why should you choose UPF-rating clothing or accessories?

According to the Skin Cancer Foundation, wearing sun-protective clothing is the simplest way to stay safe. One in five Americans will develop skin cancer by age 70, according to the SCF, and having five or more sunburns doubles your risk for melanoma. Protection is important.

The SCF recommends loose-fitting sun-protective clothing because tight clothing can stretch, reducing its level of protection as the fibers pull away from each other and allow UV rays to pass through. “The more skin your outfit covers, the better your protection,” according to the SCF. Long-sleeved shirts, pants, sun hats and sun gloves all add up to maximum coverage.


>> Shop by the entire Sun Protection Collection

>> Shop Women's Sun Shirts

>> Shop Men's Sun Shirts


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