it isn’t as it seems
What’s important is to know how to use and choose your sunblock in order to stay as protected as possible. Most people will swear by sunscreen with the highest number. It’s obvious that an SPF 100 is better than SPF 50, right? But that isn’t always the rule. When used correctly, an SPF 20 can protect you even more than an SPF 50 wrongly used!
To understand this you need to know that regardless of the product, it is important to follow the instructions and apply it regularly. To achieve a real 50+ protection you would need to use half the bottle a day. A thin layer of SPF 50 sunscreen would give you the protection of an SPF 20, that is the reason why specialists recommend higher index sunscreens.