What does the SPF value mean?

SPF stands for sun protection factor. Sunscreens are classified by an SPF number which refers to their ability to deflect UVB rays. The SPF rating is calculated by comparing the amount of time needed to burn sunscreen-protected skin vs. unprotected skin.

Another way to think about the difference between SPF levels is the amount of UVB rays that are able to filter through. SPF 15 products filter 93% of the sun’s UVB rays, meaning 7% of rays are able to filter through, while SPF 70 filters 99% of UVB rays, letting only 1% through. While those may not sound drastic, it’s the difference between the amount of rays getting through over time that add up. For example, using an SPF 15 means your skin is being exposed to seven times the amount of UVB rays vs. SPF 70.

Use a broad spectrum SPF of 30 or higher to protect not only against sunburn, but reduce the risk of skin cancer and premature skin aging caused by the sun.