SPF works by extending the time you can spend in the sun without getting burned. For example, if you typically start to burn after 10 minutes in the sun, an SPF 30 sunscreen theoretically allows you to stay in the sun 30 times longer, or about 300 minutes, without burning. However, this is an approximation and varies based on factors like skin type, the intensity of sunlight, and the amount of sunscreen applied.
