Dear Elmo,
What does UPF50 mean?
An immediate assumption may be that UPF50 only blocks 50% of the sun’s rays. That’s not true. It actually blocks 98% of the sun’s rays.
The 50 indicates that 1/50th of the sun’s rays are able to penetrate the fabric, which calculates to 2%. That means 98% of the rays are blocked.
Using that same formula, we can calculate that:
- UPF25 allows 1/25th, or 4%, of the sun’s rays to penetrate. 96% are blocked.
- UPF30 allows 1/30th, or approximately 3%, of the sun’s rays to penetrate. 97% are blocked.
You get the idea
To look at it another way:
- Good sun protection: UPF15, UPF20
- Very good sun protection: UPF25, UPF30, UPF35
- Excellent sun protection: UPF40, UPF45, UPF50
What about the average white cotton T-shirt you might think is giving you a bit of protection?
Sun protection from a white cotton T-shirt rates at a UPF5. Yikes is right!
Note on this UPF50 Blog Post
This post is from a series called: Short Answers to Common Sun Shirt Questions. We could have put all the info in one big-long blog but then it would be one big-long thing to read. We’re keeping it short and sweet.
Know that when it comes to sun tips and sun shirt questions, we got you covered – in UPF sun protective clothing to be exact. Visit our Cape Life shop in downtown Cape Coral or shop online right here at UPF50.com.
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