UPF stands for Ultraviolet Protection Factor, the degree to which a fabric protects you from UV rays. All fabrics have some level of protection, but without proper testing it’s impossible to know the exact UPF rating. Continue reading to learn the role of UPF ratings in UV protective clothing.
How Do I Know If My Shirt Has a UPF Rating?
Generally speaking, if a fabric has been tested to determine it’s UPF rating you will see it somewhere on the fabric itself. It may be fused onto the inside of the shirt, or on the tag. In addition, you can also quickly look it up online to see if the UPF rating is listed in the description. If you’ve checked all of those areas and still cannot find the UPF rating, it’s likely it was never tested. While most UV protective clothing goes through the extra steps of verifying it’s rating, it’s a costly process. Most clothing without UV protection in mind will not have the fabric lab tested, and thus will not have an official UPF rating.
What Is the UPF of a Cotton Shirt?
As mentioned previously, without proper testing it’s impossible to provide an exact number. There are a lot of different factors that impact a shirt’s UPF rating, so every shirt is different. However, a good rule of thumb for a fairly standard cotton shirt is to assume a UPF rating of about 5. UV protective clothing has a minimum rating of UPF 15, so 5 is far below anything professionals would consider ‘protective’. The following video provides a great summary of the difference a UPF rated shirt can provide versus your standard cotton shirt:
What Is Considered a Good UPF Rating for UV Protective Clothing?
The ASTM (American Society for Testing and Materials) sets the standard for the different UPF ratings in the United States. They published the below chart, which determines the ‘protection category’ of different fabrics based on the UPF rating:
|% UV Radiation Blocked
|UPF 15 – 24
|93.3 – 95.9
|UPF 25 – 39
|96.0 – 97.4
|UPF 40 – 50+
|97.5 – 98+
In summary, anything below UPF 15 does not even receive a protection category and is not considered UV protective clothing. At Rayward Apparel, we only sell apparel that has a UPF 30 rating or better, ensuring our customers are properly protected.
You may be more familiar with SPF, as it’s the rating given to sunscreens. As far as the actual rating number is concerned, they represent the same level of protection. So a UPF shirt provides the same degree of protection as an SPF sunscreen, but there are some differences which you need to be aware of:
UPF is the rating given to fabrics, whereas SPF is the rating given to different sunscreens. The number itself is the same, it determines the protection factor in which it blocks UV rays. However, there is one major difference which is important to keep in mind: UPF is inherently broad-spectrum – it blocks both UVA and UVB rays. SPF on the other hand, only rates its effectiveness against UVA rays. So when buying UV protective clothing, no need to check for a “broad-spectrum” statement. But, when you are buying sunscreen make sure it’s labeled as “broad-spectrum” so you get full protection. Both UVA and UVB rays are linked to skin cancer, so you should definitely be protecting yourself from both.