Both SPF (Sun Protection Factor) and UPF (Ultraviolet Protection Factor) are standards used to measure sunburn protection. SPF, the standard used to measure the effectiveness of sunscreens, has been around for many years. The UPF system is relatively new and was created specially for sun protective fabrics. At first, American sun protective fabrics were rated using the SPF standard until the FTC finalized the UPF standard we have today. Use of the UPF standard is voluntary so some sun protective fabric manufactures still use the SPF system.

SPF VS. UPF infographic

SPF Rating System

SPF measurements are done on human subjects. SPF, is a gauge of how much time a person can be exposed to the sun before getting burned. For example, if you burn in 10 minutes without sunscreen and you apply a liberal dose of sunscreen with a SPF number of 15, you should be protected from a sunburn for 150 minutes. Although sunscreens with identical SPF numbers give you equivalent sunburn protection from UVB rays, no sunscreen product screens out all UVA rays. Some may advertise UVA protection, but the current SPF standard does not measure the amount of UVA protection.

 

SPF Infographic

 

Although experts still believe that UVB is responsible for much of the skin damage caused by sunlight --especially sunburn-- UVA may be an important factor in other types of sun damage, including premature aging, wrinkles and the development of skin cancers. For more detailed information on the differences between UVA vs. UVB rays, check out our blog post here.

UPF Rating System

UPF measurements of fabrics are generally tested by spectrophotometer equipment and are not tested using human subjects. The UPF rate indicates how much of the sun's UV radiation is absorbed by the fabric. For example, a fabric with a UPF rating of 50 only allows 1/50th of the sun's UV radiation to pass through it. This means that this fabric will reduce your skin's UV radiation exposure by 50 times (98% UV block) in areas where the skin is protected by the fabric.

 

UPF Infographic

 

One big advantage of the UPF standard is that both UVB AND UVA are measured.

The table below illustrates the different UPF protection ranges and the percentage UV blocked. Sungrubbies products are all tested by independent laboratories and we maintain that most of our UPF products are UPF 50 +.

Protection Category UPF Range UPF Values Allowed on Labels
Approximate % UV Blocked
Good UV Protection
15 - 24
15 and 20
93.3% - 95.8%
Very Good UV Protection
25 - 39
25, 30 and 35
96.0% - 97.4%
Excellent UV Protection
40 - 50+
40, 45, 50 and 50+
97.5% - 98.0%

 

Shop our most popular products (lab tested UPF 50):
The Cruz Hat
The Wind Haven Hat

Casual Traveler Hat
Ribbon Braid 5" Hat
UPF 50 Long Sleeve Sport Shirt (Men)

UPF 50 Long Sleeve Sport Shirt (Women)
Lightweight Sungloves
Solar Face Shield

Shop Sungrubbies for Women's and Men's UPF 50 clothing, which provide 98% protection from the sun's harmful UVA & UVB rays.

 

 

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