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 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%

We tried to simplify this post so that it's easier to follow and understand. Feel free to share your comments with us.


  • Boris

    I don’t thing it’s correct that UPF takes into account both UVB AND UVA. Wikipedia says that in UPF after the UV is measured “a sunburn weighting curve (erythemal action spectrum) across the relevant UV wavelengths” is applied to the results which basically means that the result for each wavelength is multiplied by how much skin-burning it induces (if you look at the said curve it almost exclusively affected by UVB and very little by UBA which is the same for SPF).

  • Kent Mohr

    1. You don’t explain how you get 98% from 1/ 50 th reduction of UV rays.

    2. What rays give you the vitamin D and healthy tan? And do they get through my Columbia shirts?

  • Sungrubbies

    Hi Yair,
    Thanks for the comment. We follow ratings based on organizations such as the skin cancer foundation. They consider anything UPF 30+ qualified for their seal of recommendation. It is understood that a UPF 0f 30+ offers good sun protection while a UPF 50+ offers excellent sun protection. It all depends on how much and long you are exposed to the sun regularly. It also depends on the UB index rating.

    Hope this helps.

  • Yair

    Thank you for the clarification!
    One question I have is, at UPF protection is it that significant the difference between the 93% and the 98% ? Because it seems that both of them provide very high protection if looking by the numbers, so why would I care if the cloth im buying is 15 UPF or 50
    Thank you

  • Alex

    Thank you very much for the explanation it was very good

Leave a comment

Please note, comments must be approved before they are published

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.