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SPF vs. UPF- What is the difference?
SPF vs. UPF- What is the difference?
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 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.
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.
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%
|
We tried to simplify this post so that it's easier to follow and understand. Feel free to share your comments with us.
So, what does it mean when I buy a shading material and it says 80-90% shade. How would that be converted to UPF. For example, a patio umbrella that offers 80% shade, would that only block 80% of the UV rays, which is poor protection? Or would it be a UPF of 50+, which is excellent protection?
UPF is simple as UV (1/UPF) % block by the fabrics. However, is it somehow similar to SPF that since UPF block the respective percentage of UV and should also prolong the minutes as SPF offers?
@ Kent Mohr, UPF 50 reduces UV rays by 98%, allowing a maximum of 1/50th of the suns of UV to get through. 2% is 1/50th of 100%.
If I were to wear two (2) UPF 50+ shirts would that then block all 100x or 100% of the suns UV radiation? Would a thicker product block more UV radiation versus the thin materials currently available? Basically if you double the thickness of the material will it block 100% UV?
But i am curious what about the breathable holes? Will that area be protected the same on the hat?
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