Understanding UPF ratings for the best sun shirts

UPF is to sun shirts as SPF is to sunscreen. A fabric with a numeric rating has been tested in a lab to measure how much ultraviolet light can pass through. UPF 15, for example, allows 1 UV ray out of every 15 rays to pass through. The same is true for UPF 30, 50, and so on. And much like sunscreen, UPF 15 is a good baseline that should protect you adequately in moderate to high levels of sun exposure.

However, in situations involving extreme sun exposure, such as walking on glaciers or at extremely high altitude, the best sun shirts are those rated to UPF 50+. In order to increase its UPF rating, a fabric needs to be thicker and/or darker, which is not desirable when you want to stay as cool as possible in hot sunny weather. Thus, for optimal comfort, you should choose a sun shirt with only as high of a rating as is necessary for the expected level of UV exposure.

Sun hoody vs t-shirt

When choosing between different hiking shirt chassis configurations, know that the best sun shirts are long sleeve pullover hoodies. This provides maximum skin coverage without the discomfort/inconvenience of weight, zippers, or buttons. Good sun shirts are so highly breathable that they hardly benefit from zipper venting anyway.

And again, because they’re so light and breathable, you barely notice the sleeves and hood, but they’re always there when you need them to protect you from UV. As an added bonus, they significantly decrease how much sunscreen you’ll need to use.

When are long sleeve button ups the best hiking shirts

We recommend a traditional long sleeve button up hiking shirt over the best sun shirts for the following scenarios: You are bushwhacking and require a more durable fabric that won’t snag and tear. Or you are concerned about swarms of mosquitoes landing on you and biting through thin fabric.

Thanks to their tough woven nylon, long sleeve button-up hiking shirts are more bite resistant than the typical stretchy, knit polyester sun shirt. And since they’re thicker, woven nylons are almost always rated to UPF 30 or higher. We haven’t seen large performance deltas between different models, they’re all roughly the same. Whatever you can find that is lightweight, fits well, and is conveniently priced is probably the best option.

While we appreciate long sleeve button ups for their protective qualities, they are significantly less breathable and less stretchy than knit polyester sun shirts, so you should only choose to wear one when the situation calls for it. Nonetheless, the long sleeve button up hiking shirt is still a relevant and viable option.

Treat your hiking shirt to protect against bugs

For hiking in mosquito season, we recommend wearing a designated bug shirt. This is usually a long sleeve button up, made of woven nylon, that has been treated with Sawyer spray-on permethrin. Permethrin is a chemical insect repellent for mosquitos, ticks, and other insects that is safe for humans. Insects are repelled by the smell of it and their nervous system is harmed by being in its presence.

In some cases, you can use your best sun shirt as your bug shirt, but people prefer to have a separate, designated garment.

We reapply a new coat of permethrin to our bug shirt  once or twice per season, depending on use. It lasts many washes. This stuff really works, and when used properly in conjunction with a head net and sawyer Picaridin for protecting exposed skin, is part of a system that creates a very strong swarm-proof insect repellent aura around your body.

Considerations on color for the best hiking shirts

There are a few performance factors to think about when choosing between color, aside from personal taste and preferences.

Sun Shirt Heat Absorption

For starters, a lighter hiking shirt is more reflective of sunlight, compared to a darker shirt which absorbs it. A white shirt would feel cooler than a black shirt in direct sunlight. However, lighter shirts are also more sheer, which makes them slightly less effective at blocking ultraviolet light. Take our top pick, the Outdoor Research Echo Hoody, for example. The off-white colorway is rated to UPF 15, whereas all other colorways are rated to UPF 20.

In general, we recommend lighter colors, so long as they don’t drop you below UPF 15. For the Echo specifically, we would always choose colors rated to UPF 20 since it’s a free upgrade so long as you don’t choose the off white.

Insect Attraction

Additionally there are some considerations around how insects interact with color, though this hasn’t been proven outside of a lab. However, it would seem that mosquitos are slightly more attracted to red, orange, black, and cyan, and less attracted to green, blue, white, or purple.

Hunting

A third and final concern would be safety – a bright red, orange, or yellow shirt would make you more easily identifiable in a rescue situation, while also providing added visual awareness safety during hunting season.

A sun shirt is a base layer

Just to clarify, you don’t need to wear anything underneath a sun shirt, it will act as your base layer. All of the best sun shirts are soft on skin, wicking and quick drying, thus wearing anything underneath, like a tee shirt or tank top, will just add extra fabric and make you hotter.