Here in southern Utah, sun protection isn't a nice-to-have — at 2,800+ feet of elevation with 300 days of sunshine, UV exposure is the single most predictable hazard on any trail. Sunscreen helps, but it sweats off, gets missed, and needs reapplying. Clothing doesn't. Here's how to read the ratings and choose gear that genuinely protects.
UPF vs. SPF: Same Idea, Different Surface
SPF rates sunscreen. UPF (Ultraviolet Protection Factor) rates fabric — it's the ratio of UV radiation that reaches your skin without the fabric versus with it (Wikipedia). A UPF 50 fabric lets through just 1/50th of UV — about 2%, blocking 98%.
One crucial difference: SPF only measures UVB (the burning rays). UPF covers both UVA and UVB — and UVA is the wavelength most responsible for long-term skin aging and damage.
| Rating | UV blocked | Classification |
|---|---|---|
| UPF 15–24 | 93–96% | Good |
| UPF 25–39 | 96–97% | Very good |
| UPF 40–50+ | 97.5–98%+ | Excellent |
For reference: an ordinary summer T-shirt is roughly UPF 6 — and less when wet (Wikipedia).
What Makes a Fabric Protective
No lab coat needed — four things drive UPF (REI Expert Advice):
- Weave density. Tighter weave = smaller gaps for UV. Hold fabric up to the light; the more light through, the more UV through.
- Color. Darker and more vivid colors absorb more UV than pale ones.
- Fiber type. Polyester and nylon disrupt UV better than bleached cotton.
- Condition. Wet, stretched, or threadbare fabric loses protection.
The Hat Question: Coverage Beats Everything
A cap protects your forehead and nothing else. The parts of you that actually burn on the trail — ears, neck, temples — need brim coverage. Rules of thumb:
- 3-inch brim minimum for real protection, all the way around
- A neck cape or long back panel is worth its weight in aloe on exposed routes
- Ventilation matters — a hat you take off because you're hot protects nothing. Mesh panels trade a little UPF for a lot of wearability
- A chin cord keeps the hat on in canyon wind
That's the design logic behind wide-brim styles like our Men's Wide Brim Mesh Bucket Hat and the Dakine No Zone Cap, which pairs a wide brim with a long back panel and ear vents — one wearer called it "great for hikes, breathable," with adjustable cords that keep it secure "in strong winds."
The Complete Sun System
Clothing and hats handle what they cover. For everything else:
- Sunscreen on exposed skin — face, hands, any gap in coverage. Reapply every two hours of sweating.
- Sunglasses — UV damages eyes cumulatively, and snow/sand/water reflect UV upward under your hat brim.
- Timing — UV peaks between 10am and 4pm. Desert hikers who start at dawn aren't just beating the heat.
- Aftercare — even careful people overdo it. Aloe vera gel rehydrates sun-stressed skin and is the single most-restocked item in our Sun, Skin & Bug Protection collection for a reason.
The Takeaway
UPF is one of the few gear ratings that's genuinely simple: UPF 50 = 98% blocked, and coverage area matters as much as the number. A wide-brim UPF hat plus a long-sleeve sun shirt out-protects any amount of sunscreen you'll realistically reapply — and it never wears off at mile eight.
Sources: REI Expert Advice — How to Choose UPF Clothing, Wikipedia — Sun Protective Clothing, Academy — UPF Clothing Guide