What is the difference between UPF and SPF?

The difference between UPF and SPF relates to their specific functions and applications in sun protection. UPF stands for Ultraviolet Protection Factor, and it measures the effectiveness of a fabric in blocking ultraviolet (UV) radiation from the sun. A higher UPF rating indicates greater protection against UV rays. For example, a fabric with a UPF of 50 allows only one-fiftieth of UV radiation to pass through, providing significant protection compared to typical clothing. On the other hand, SPF stands for Sun Protection Factor, and it is primarily associated with sunscreen products. SPF indicates the level of protection the sunscreen provides against UVB rays, which are the rays that cause sunburn and contribute to skin cancer. An SPF rating is essentially a measure of the time it takes for skin to burn when using the sunscreen compared to unprotected skin. For instance, if an individual normally burns after twenty minutes of sun exposure without protection, using a sunscreen with an SPF of 30 would theoretically allow them to stay in the sun thirty times longer without burning. In summary, UPF is a rating for the protective qualities of fabrics against UV radiation, while SPF is a rating for the performance of sunscreen products against UVB rays. For effective sun protection, it is advisable to combine both UPF clothing and SPF sunscreen for comprehensive coverage when spending time outdoors.