What’s the SPF Magic Number?The SPF or Sun Protection Factor indicates the level of protection that particular sunscreen gives you as compared to no sunscreen. The time it takes for a sunscreen to wear off depends on the length of time it takes for your skin to burn without protection. For example, if it takes your skin 10 minutes to burn without sunscreen, then an SPF of 20 gives you 20 times the protection or 200 minutes until you burn. Here’s an equation to help you figure out what you need: Minutes to burn without sunscreen x SPF number = maximum sun exposure time
Misleading InformationThis summer, companies have launched SPF 70 sunscreen, which might lead you to think that you could be in the sun for 12 hours based on the aforementioned formula. BUT, consumers don’t typically put the same amount of sunscreen on as is applied during testing. Therefore, you’re likely to get less out of the SPF rating than the formula would suggest. For best results, you should:
- Apply sunscreen 15-30 minutes before sweating or entering water because the best protection is given when the sunscreen has time to soak in.
- Reapply every 30 minutes to an hour, depending on skin type and age.