Do UPF Shirts Really Work? (Yes—Here’s the Proof)
It sounds too good to be true—can a shirt really protect your skin from the sun? The answer is yes. But not just any shirt will do. UPF (Ultraviolet Protection Factor) clothing is specifically designed to block harmful UV rays, and it's backed by lab testing and dermatological research. In this post, we’ll break down how UPF shirts work, what to look for and why JOJU’s UPF 50+ sun shirts are the real deal.
☀️ What Does UPF 50+ Actually Mean?
How is UPF different from SPF?
SPF is for sunscreen; UPF is for fabric. SPF measures how long a product protects you from UVB rays. UPF measures how much UVA and UVB radiation passes through fabric. A UPF 50+ rating means that less than 2% of UV rays can reach your skin.
What makes a shirt UPF-rated?
UPF-rated shirts are tested in labs to measure how much UV radiation they block. This depends on:
Fiber type (synthetics like polyester block more than cotton)
Fabric construction (tight weaves = less UV penetration)
Color (darker colors generally block more rays)
Moisture management (wetness can lower protection in poor-quality fabric)
🧪 The Science: Lab Testing vs. Marketing Hype
How are UPF shirts tested?
Each of our products is lab tested and certified in accordance with AATCC Test Method 183 , the standard test method used in the United States. The AATCC-183 measures the UV radiation blocked or transmitted by fabrics intended to provide UV protection. Think of it like the SPF of sunscreen (UPF is to clothing as SPF is to sunscreen). Click here for details.
Can regular shirts do the same?
No. A white cotton T-shirt has a UPF of about 5. That means 20% of UV rays pass through —and even more when the shirt is wet. UPF clothing offers exponentially better protection.
🎾 Why Dermatologists Recommend UPF Clothing
Is UPF better than sunscreen?
UPF shirts offer consistent, all-day coverage —no reapplying, no sweating it off. Dermatologists often recommend UPF clothing as a first line of defense, with sunscreen used on exposed areas.
Who should wear UPF clothing?
Everyone—but especially:
People with fair or sensitive skin
Anyone spending long hours outdoors
Children, athletes, and sun-conscious travelers
Want expert-backed peace of mind? JOJU’s fabric is tested in U.S. labs, not just “claimed” to be protective.
🧵 What Sets JOJU Apart
Not just UPF—elevated performance
JOJU shirts combine:
- Italian performance fabric
- Featherlight comfort
- Slim, flattering cut
- UPF 50+ that lasts (even when wet or washed)
Bonus: You’ll actually want to wear them—from tennis court to brunch.
💬 FAQ
Does UPF wear off after washing?
Not with JOJU. Our UPF is woven into the fibers, not applied as a coating, so it won’t wash out.
Do JOJU shirts protect when wet?
Yes. Unlike cotton, JOJU fabric maintains its UPF 50+ rating even after a swim or sweaty workout.
How do I know if a shirt is really UPF 50+?
Look for lab-certified testing, not just marketing claims. JOJU’s shirts are tested in U.S. labs for verified sun protection.
